Bug fix for upsert of 0.0
Error if column family starts with underscore
changes for dropping multiple columns
Drop columns feature
Most of nanos fix
Using utility function for creating timestamps
More nanos cleanup
Remove testUpsertFloat as it's causing merge nightmares
More nanos testing
Remove nanos test
Added test for timestamp
Fix for UpsertValuesTest.testTimestampAddSubtractArithmetic()
Rest of nanos fix
Add missing expressions to ExpressionType and increase version to 2.2.0
Don't coerce TIMESTAMP to TIME/DATE
fix version number on 2.1.2 branch

selective revert of 08b2b336498fd50d510fa6c2b81065ffb658c518