minor fluid-vec fixes to parse non-zip files

Simpllify the map API.
Bug in Frame.toString
Bug in parsing TAB as whitespace instead of seperator
merge; BigVector -> Chunk
Merge branch 'master' of github.com:0xdata/h2o

Conflicts:
	src/main/java/water/MRTask2.java
	src/main/java/water/fvec/ParseDataset2.java
	src/test/java/water/fvec/FVecTest.java
Merge branch 'master' of github.com:0xdata/h2o