Add logging for missing shard
Allow plugin files to add subprocess flags for site-local packages.
Adding a Logger interface, tests and using it.

This is so we can have background operations that log,
and keep the logs. We can then display them on a web page
or on the console depending on the usage.
(this is part of vtctl refactor).
Separating out ConsoleLogger.
Using the logger in a few more places.
Workers now use Logger.
Merge branch 'master' of github.com:youtube/vitess
Merge branch 'master' into replication
Filter out events from unwanted databases in binlog stream.
Merge branch 'master' into replication
Fixing unit tests.
Add ServiceContext to isolate internal and external ServiceManager APIs.