Removing zkocc from zkocc_test.py. Now it's only a topology test.

(keeping it with a weird name as it'll go away once vtgate v2 is
the only supported way to make queries).
Removing more zkocc tests.
Removing zkocc and related files.
Using an explicit config for this openssl command.

Otherwise it depends on openssl's default config, which may not be right.
Don't check ctx.Err() unless ctx.Done() was closed.

The zktopo lock tests have been flaky, with errors saying "interrupted".
This was because there's a race condition where ZK can time out before
the ctx.Done() channel has been closed, so ctx.Err() returns nil and we
return the wrong topo error (interrupted instead of timeout).
Add unit tests for etcdtopo.
Add topo tests for deleting keyspace, shard, etc.
Reject lock attempt on nonexistent keyspace/shard.
Fix panic and hang in etcdtopo lock.

Found during integration tests:
- Panic was because nil *Response is returned on error.
  Updated fake etcd client to reflect this.
- Hang was because released locks were setting empty contents
  instead of the new magic value.
Set non-zero default for vtctl lock timeout.

Elsewhere it was decided that we should adopt the Context convention
that a timeout of 0 really means time out immmediately. The vtctl
default of 0 was causing timeouts in places that respect ctx deadlines,
like etcdtopo.
Wait for both mysql.sock and mysqlctl.sock.

I switched from SSD to RAM disk and it exposed a race condition.
When launching mysqlctld in the background, we need to wait for both
mysql.sock and mysqlctl.sock to show up before we try to connect.
Wait for mysqlctld to terminate before continuing teardown.

Another race condition exposed by RAM disk:
We were sending SIGTERM to mysqlctld, but not waiting for it.
Then we proceed to delete all the data files. If the deletion is fast
enough, it can remove files that mysqlctld needs to do its teardown, and
mysqld processes are left orphaned.
v3 proto: prep work to support streaming
Fixing a number of golint issues.
ensure syslogd is up before starting the build

test/schema.py uses log/syslog which requires a running syslog daemon
and the start script should guarantee it is up and running.
let travis build status ref master branch only
Add vtctld explorer plugin for etcd.
Linter fixes.
Better linter fixes.
Fix case for disable_query_service flag