Update example in deployment instructions
Add docs for MySQL and PostgreSQL connectors
Add missing @Override annotations

These were found by static code analysis in Eclipse.
Fix issues found by findbugs
Add support for reading data from MapR
Change Cassandra properties to use Duration
Fix TestSqlStageExecution.testSplitAssignment()
Split TestingPrestoClient into base and implementation

This allows other clients to use the infrastructure to pull data out
of a presto server. The Kafka test suite uses this to pull data out of
tpch and write it into the Kafka topic out-of-band (the kafka
connector is read-only).
Add Kafka connector