Remove unused methods on Page
Convert Page size to be a long in bytes

Simplify OperatorContext stats
Remove Page dependencies on Guava
Remove Page.getSingleValueBlocks(position)
Move Page to SPI
Remove PageBuilder dependencies on Guava
Move PageBuilder to SPI
Add ConnectorPageSource to SPI

Move ConnectorDataStreamProvider to SPI and rename to ConnectorPageSourceProvider
Simplify InformationSchemaPageSourceProvider using a FixedPageSource
Replace AlignmentOperator with RaptorPageSource
Merge InternalConnector into Connector
[cassandra] Bump to current stable version.

The 2.0.0-rc2 driver has a bug
(https://datastax-oss.atlassian.net/browse/JAVA-254) which gets
triggered when querying through presto.  An exception occurs because the
driver attempts to query a table that no longer exists, and fails.

Cassandra 2.1.0 is the current stable release, so it's probably time to
catch up.  The hector library has been removed and replaced, because it
didn't seem to work correctly with C* 2.1, and the project doesn't
appear to be very active.