Record input stats for PageSource
Sort classpath for plugins from POMs
Remove redundant classes directory for plugins

The target/classes directory is already included in the resolved classpath
returned by the artifact resolver.
Use canonical file names for plugin classpath
Add debug logging for plugin installation
Replace Block.release() with Block.assureLoaded()
Add HiveType.toString()
Add support for NULL parition keys
Add support for TIMESTAMP in Hive partition key

Fixes #1474
Add Hive write support for varbinary, date and timestamp

Fixes #1425
Allow OrcHiveRecordCursor with no columns
Verify JVM timezone in HiveQueryRunner for tests