sendReply -> sendTransaction
include statement types in BinlogTransaction
fix binlog_streamer_test
New EventStreamer API for update stream

The new API is different from binlog_parser because
it only transmits the group id. Also, the API now
sends differnt object types (DDL, DML, or position).
The new position is only sent at the end of a transaction.
This ensures that retries will cause the events from the
current transactions to be resent in case of mid-transaction
failures.
Typ->Category
Merge branch 'new-binlog-streamer'
Vtctld redirects for the serving graph.
Merge branch 'master' of github.com:youtube/vitess
failure tests for event_streamer
Merge branch 'master' of github.com:youtube/vitess
Merge branch 'master' into replication
event_streamer positive tests
Merge branch 'new-binlog-streamer'
Merge branch 'replication'