rake generate not working

[lokeshh]

I get the following error when I do rake generate :

## Generating Site with Jekyll
   remove .sass-cache/ 
   remove source/stylesheets/screen.css 
   create source/stylesheets/screen.css 
Configuration from /home/ubuntu/workspace/sciruby.com/_config.yml
Building site: source -> public
2013-10-12-ruby-and-the-semantic-web-rdf-sparql-publisci.markdown
2012-09-24-second-nmatrix-alpha-released.markdown
2014-07-28-benchmarks-for-integration-gem.markdown
2012-05-08-sciruby-summer-of-code.markdown
2012-07-31-major-refactoring-in-the-pipeline.markdown
2014-07-02-usage-integration-gem-improvements.markdown
2015-08-19-gsoc-2015-mixed-models.markdown
2012-05-23-sciruby-summer-of-code-selection-announced.markdown
2014-02-24-gsoc-2014.markdown
2012-02-11-numeric-matrix-considerations.markdown
2014-07-02-progress-of-d3-project.markdown
2013-09-24-gsoc-2013-data-mining-in-jruby-with-ruby-band.markdown
2011-11-02-first-pre-alpha-release.markdown
2013-11-07-statistics-with-ruby-time-series-and-general-linear-models.markdown
2015-08-18-gnuplotrb-project.markdown
2014-06-19-progress-on-minimization-methods.markdown
2014-06-04-introduction-to-the-minimization-and-integration-project.markdown
2011-08-17-interview-with-the-sciruby-team.markdown
2014-06-04-introducing-the-fftw-sciruby-gsoc-project.markdown
2014-08-23-nyaplot-interactive-plots-generateor-with-ruby.markdown
2013-11-01-call-for-funding-more-women-needed-in-open-source-science-software.markdown
2012-04-11-first-nmatrix-alpha-released.markdown
2015-02-14-nmatrix-beta-released-belated-announcement.markdown
2014-06-24-updates-minimization-and-integration.markdown
2014-06-02-introducing-gsoc-2014-the-d3-project.markdown
2011-08-15-the-challenges-of-copyrights.markdown
2014-06-18-introduction-minimization-and-integration.markdown
2015-08-19-gsoc-2015-nmatrix.markdown
2012-12-07-how-to-use-nmatrix-shortcuts.md
2015-08-17-ruby-wrappers-for-symengine.markdown
2012-09-24-sciruby-receives-ruby-association-grant--fellowships-available.markdown
2014-01-27-gsoc-alumni.markdown
2011-08-15-first-post.markdown
2013-09-18-nmatrix-nearing-beta-release.markdown
2014-07-09-nyaplot-internal-event-handler.markdown
2012-11-28-spring-2013-sciruby-fellows-selected.markdown
2015-08-16-summary-of-work-on-daru-this-summer-for-gsoc-2015.markdown
2013-10-25-mentoring-future-computational-power-women-for-gci-2013.markdown
/usr/local/rvm/gems/ruby-2.1.0/gems/ffi-1.0.11/lib/ffi/library.rb:121:in `block in ffi_lib': Could not open library 'lib.so': lib.so: cannot open shared object file: No such file or directory (LoadError)
        from /usr/local/rvm/gems/ruby-2.1.0/gems/ffi-1.0.11/lib/ffi/library.rb:88:in `map'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/ffi-1.0.11/lib/ffi/library.rb:88:in `ffi_lib'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/rubypython-0.5.3/lib/rubypython/python.rb:29:in `<module:Python>'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/rubypython-0.5.3/lib/rubypython/python.rb:21:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/rubypython-0.5.3/lib/rubypython.rb:261:in `load'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/rubypython-0.5.3/lib/rubypython.rb:261:in `reload_library'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/rubypython-0.5.3/lib/rubypython.rb:104:in `start'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/pygments.rb-0.2.13/lib/pygments/ffi.rb:8:in `start'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/pygments.rb-0.2.13/lib/pygments/ffi.rb:82:in `highlight'
        from /home/ubuntu/workspace/sciruby.com/plugins/pygments_code.rb:24:in `pygments'
        from /home/ubuntu/workspace/sciruby.com/plugins/pygments_code.rb:14:in `highlight'
        from /home/ubuntu/workspace/sciruby.com/plugins/backtick_code_block.rb:37:in `block in render_code_block'
        from /home/ubuntu/workspace/sciruby.com/plugins/backtick_code_block.rb:13:in `gsub'
        from /home/ubuntu/workspace/sciruby.com/plugins/backtick_code_block.rb:13:in `render_code_block'
        from /home/ubuntu/workspace/sciruby.com/plugins/octopress_filters.rb:12:in `pre_filter'
        from /home/ubuntu/workspace/sciruby.com/plugins/octopress_filters.rb:28:in `pre_render'
        from /home/ubuntu/workspace/sciruby.com/plugins/post_filters.rb:112:in `block in pre_render'
        from /home/ubuntu/workspace/sciruby.com/plugins/post_filters.rb:111:in `each'
        from /home/ubuntu/workspace/sciruby.com/plugins/post_filters.rb:111:in `pre_render'
        from /home/ubuntu/workspace/sciruby.com/plugins/post_filters.rb:166:in `do_layout'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/lib/jekyll/post.rb:189:in `render'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/lib/jekyll/site.rb:193:in `block in render'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/lib/jekyll/site.rb:192:in `each'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/lib/jekyll/site.rb:192:in `render'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/lib/jekyll/site.rb:40:in `process'
        from /usr/local/rvm/gems/ruby-2.1.0/gems/jekyll-0.11.2/bin/jekyll:250:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.1.0/bin/jekyll:23:in `load'
        from /usr/local/rvm/gems/ruby-2.1.0/bin/jekyll:23:in `<main>'
        from /usr/local/rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `eval'
        from /usr/local/rvm/gems/ruby-2.1.0/bin/ruby_executable_hooks:15:in `<main>'

The octopress site I'm trying to run is https://github.com/SciRuby/sciruby.com