Moving an init.
Adding a cache with a 1s TTL to vtgate topo server

And a qps test. In front of zookeeper, qps is now 36-38k,
compared to 45-47k qps for zkocc. So we're very comparable,
for a much simpler implementation that doesn't rely on watches.
Fixing data race in context. And it's faster too.
More descriptive error messages.
Fix error messages.
Various small fixes.
Merge branch 'master' into replication