hardcoded absolute paths in meta.hbs

[drfraser]

Hi, I put my blog at a directory below root of the website, so all the '/assets/img/....' links in meta were resulting in errors. Easy fix: I put

{{asset "path to file"}} in place and removed all the ?v=.... parts as Ghost adds that sort of thing dynamically (so they shouldn't be there)

No idea yet if there is are other relative paths that don't get corrected, so I also added a base HTML tag to deal with that.