Add comment field in DESCRIBE TABLE
Update to new ColumnMetadata api
Change column comment to be empty string instead of null
Configurable Hive SerDe, InputFormat, OutputFormat in CreateTableAsSelect

Closes #1453
added number of runs and fixed time zone header
Factor a TestingPrestoClient out, add a single node server query runner.

This removes the query specific code from the DistributedQueryRunner
and adds a new QueryRunner that uses a real, albeit single-node,
embeded discovery TestingPrestoServer. Unlike the LocalQueryRunner
which fakes a presto engine, this is a full-fledged server.
Upgrade to Jax-rs 2.0 and Jersey 2.9.1
Change "verifier-test-" to "verifier-test:"
added readme for cassandra client socket options
Fix valueIsNull creation in Block.getRegion
Fix VariableWidthBlock.toString()
Print "SKIPPED" instead of an empty message when skipping a query
Fix NPE when control cluster is unreachable
Mark results as not matching, when number of columns doesn't match
Add exponential backoff when reading from S3

Closes #1332
Fix analyzer issue when "is not null" is used in join clause

Fixes #1479
Improve "too many failures" error message
Fix checkstyle violations
Fix zone offset minutes calculation

And a typo at return type of 'localtimestamp' in the datetime document

Closes #1482
Add better feature normalizer to ML plugin