vtgate v3: select plans
vtgate v3: more formal tests
vtgatev3: Gate* -> VTGate*
vtgate v3: wire plan building into vtgate
vtgate v3: add forgotten planner.go
parser: AND has higher precedence than OR
vtgate v3: add tests for or clauses
vtgate v3: make code reusable to prep for dmls
vtgate v3: update plans
vtgate v3: plans for delete
Refactoring rebuilding of keyspace.

So it's more efficient, and can support my next changes
(making ServedTypes per-cell).
Remove obsolete zk Docker example.

The useful parts of the zk Docker example have been absorbed into the
Kubernetes example. The Docker-only version is now broken anyway and
there's no point in fixing it since we're not planning to flesh out the
rest of Vitess in Docker-only mode.
vtgate v3: drop keyspace_id col & add IsAutoInc.

We're going to see if keyspace_id column based sharding
can be deprecated in favor of an on-the-fly hash based
sharding which achieves the same thing.
Also, we should support auto-inc through lookup so we
can generate systemwide unique ids for our keys.
Add a mechanism to log private data from exceptions and use case for bind_variables.
First part of per-cell horizontal sharding support.

Still needs:
- disabling query service on sources.
- unit tests for shard methods.
Merge branch 'master' into replication
Merge pull request #119 from youtube/liguo

Enable test_rollback after bug fix
fakezk: fix create node with prefix sequence
More coverage in this test case, better checks of the queries.
Merge branch 'master' into resharding