Add date dbf support

[kd35a]

No description provided.

[codecov-io]

Codecov Report

Merging #223 into master will increase coverage by 0.01%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master     #223      +/-   ##
==========================================
+ Coverage   90.16%   90.17%   +0.01%     
==========================================
  Files          52       52              
  Lines        1789     1792       +3     
  Branches      124      125       +1     
==========================================
+ Hits         1613     1616       +3     
  Misses        176      176

Impacted Files	Coverage Δ
src/main/scala/magellan/mapreduce/DBReader.scala	93.93% <75%> (+0.28%)	⬆️

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[harsha2010]

Thanks for adding this and cleaning up the code! This looks good, am merging it in