Adding a CreateShard command.

Adding a -parent option to InitTablet, so it can then
create the Keyspace and Shard. If no specified, it doesn't
even try to create them. This is more consistent.
Merge branch 'master' of github.com:youtube/vitess into reparent-fix
Merge pull request #13 from youtube/reparent-fix

Adding CreateShard, and related fixes.