Fix regression with VARCHAR partitions in Hive

Fix the Hive connector to return Slice objects for the values of VARCHAR
partition columns instead of String objects. Also fix the Hive tests to
use Slice instead of String.
Static import Slices.utf8Slice
Simplify expression
Add check for unsupported Hive partition type
Simplify test table creation for S3
Fix JSON serialization of TimeWithTimeZone and TimestampWithTimeZone

Add test to verify serialization
Prefix date time type classes with Sql
Replace use of java.sql date time classes with custom classes

Add custom classes for all sql date time types.  This makes it easier to control
the things like serialization.  Additionally, java.sql types loose information
like session time zone.
Add support for time* with timezone in JDBC
Fix JSON serialization of interval types
Add support for interval types to JDBC driver
New CLA form
Fix exchange client leak when queries are abandoned

The query purger in StatementResource wasn't calling close() on query objects when purging
them from the list of active queries. As a result, abandonded queries would result
in StatementResource leaking an exchange client
Update to airbase 19

This updates Jetty to 9.1.4, which we hope will fix https://github.com/facebook/presto/issues/1138
Add comment field in DESCRIBE TABLE