Enable rowcache in Kubernetes example.

Without it, we can't do ApplySchemaShard -simple, because the replicas
will never notice the new schema and will fail to build query plans.
Add Kubernetes config for vtgate, and a sample vtgatev2 client.
vtgate v3: remove VTGate prefix from planbuilder
vtgate v3: comprehensive schema tests
Use vitess/base Docker image for client commands.

Instead of running as root with vitess/root. The user shouldn't need to
download any additional image since vitess/root has vitess/base as a
dependency.
Read topology from vtgate.

This is a temporary work-around until the VTGate V2 client is
topology-free.
Merge pull request #142 from youtube/replication

Replication
Merge pull request #140 from youtube/docker

Add Kubernetes config for vtgate, and a sample vtgatev2 client.
vtgate v3: comprehensive tests for select
vtgate v3: add comments to v3 specific files
Merge pull request #143 from youtube/vtgate

Vtgate
Rename GetMRSplits to SplitQuery

The functionality is not specific to MapReduce, any job that wants to
split a large query into non-overlapping sub queries can use this end point.
SplitQuery should be shard agnostic

Specify total number of splits instead of splitsPerShard
vtgate v3: planbuilder unit tests complete
Rename QuerySplit to SplitQueryPart
Merge pull request #144 from youtube/split-query

Minor refactor of GetMRSplits
Add a hook to zk TestServer for use in tests.
Expand lock to avoid race in RebuildShard.

Lock before reading topo, to prevent another rebuild from writing
fresher data that could then be overwritten with stale data by a slow
rebuild.
Merge pull request #145 from youtube/rebuild

Expand lock to avoid race in RebuildShard.
vtgate v3: planbuilder cleanup