Shapefile types extent

[Charmatzis]

This PR has included support for dbf files field types Logical and Dates

[codecov-io]

Codecov Report

Merging #192 into master will increase coverage by 0.13%.
The diff coverage is 97.29%.

@@            Coverage Diff             @@
##           master     #192      +/-   ##
==========================================
+ Coverage   89.57%   89.71%   +0.13%     
==========================================
  Files          48       48              
  Lines        1564     1585      +21     
  Branches      103      108       +5     
==========================================
+ Hits         1401     1422      +21     
  Misses        163      163

Impacted Files	Coverage Δ
src/main/scala/magellan/Shape.scala	48.64% <0%> (ø)	⬆️
src/main/scala/magellan/Polygon.scala	87.75% <100%> (ø)	⬆️
src/main/scala/magellan/mapreduce/DBReader.scala	95.23% <100%> (+1.58%)	⬆️

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