Updates to fix SQL Handler issues.  Add simple full query jdbc test execution (no results checking)
fix parquet query test
fix rebase
implemented left and inner join types
Separate out JDBC drivers between ref (RefDriver) and full exec so that they don't fight with each other in the same JVM.
Add ClassPathFileSystem to support reading from classpath
Update merge join to support left and right by flipping right.
Added nullable support to parquet reader.