Make scatter streaming queries work

VtGate sends duplicate field data for each shard in a scattered
streaming query. Currently the client incorrectly treats this as end of
stream since it does not see any rows. Adding a fix to ignore responses with no rows and fetch the next set.
Integration tests refactor

Move streaming tests to its own test class
Move util stuff to package
Comments for tests
Better error messages from binlog streamer.
Merge branch 'master' of github.com:youtube/vitess
Merge branch 'binlog'
Adding a test to make sure the new master knows it's a master.
Merge branch 'master' of github.com:youtube/vitess