Update docs for MariaDB support.
Fix BinlogStreamer for MariaDB.
Now vttablet can start without mysqld running, even in healthcheck mode.

So the mysql port is completely optional. We still try to backfill it
when we can, but it's never fatal.
Merge branch 'master' of github.com:youtube/vitess
InitializeConnections works on serving tablet types only.
Add note about setting VT_MYSQL_ROOT if necessary.
Fix logic in InitializeConnections
Merge branch 'liguo'
Merge branch 'master' of github.com:youtube/vitess
vtgate: add panic handling for public functions
Add MultiSnapshot and MultiRestore events.
Merge branch 'suguwork'
optimize vertical_split.py test

We don't need to wait one second for the schema updates
any more since reload schema can handle these now.