Large refactor for Java VtGate client

Use joda.DateTime instead of java.util.Date
Refactor RpcClient to pass around objects instead of Maps
Make SplitQueryRequest and SplitQueryResponse
Revisit data types for bind variables and field types
Format changes only, using a better formatter
Add BindVariables to batch queries, do not use maps

Add set up command to test
Insert fewer rows for faster tests
Merge remote-tracking branch 'origin/refactor-vtgate'