Modified parser to handle multiple keys (value arrays).

All keys are parsed into single value array. Basically parses each file separately in a loop, with extra step to put information together after pass 1( to compute global compression scheme) and to set correct output chunks in pass2.

Also, added tests and utility method Value.isBitIdentical(Value).
Fix for key of length 1 (used to throw aiob when persisting to disk)
Merge branch 'master' of github.com:0xdata/h2o
just added few comments to my recent commit.