pool: support for timeout and delete RoundRobin

We need timeout support for ResourcePool. This is a good time
to also delete the deprecated RoundRobin.
fix some typos
query_service: use accurate timeouts for queries

The fixed timeout active_pool cannot support queries with different
deadlines. Replace that with a scheme where queries can have
specific deadlines.
Merge branch 'vtocc'
Merge branch 'master' of github.com:youtube/vitess
Making verbosity in RPC configurable.
Turning it off for TabletExternallyReparented as decider
spams us with it all the time.