Fix to list of cells to build serving graph in.

When re-building a Keyspace that is ServedFrom another
keyspace, we need to save the SrvKeyspace object in all the
cells from the ServedFrom keyspace as well.
Merge branch 'replication'
Simplifying RebuildShard call.
Fixing / adding messaging.
Implementing copy of snapshots to central storage.

This uses specialized hooks, with sample versions for tests.
Have to re-run bootstrap.sh to pick them up.
Avoid serializing to string in streamlog.

Some log consumers wish to receive structured messages. This is best
evidenced by the logz handlers parsing the message strings they receive.
Implement error case of downcasts in streamlog consumers.

This should never happen (famous last words).
Moving a few status functions to this source tree.

They allow the status page of vttablet to be better.
Also testing this code in vtctld_test, so we make sure the
templates work. And manual inspection works very well too.
Merge commit 'f7df4e7e97e66a6b3f3a9b2ea5645ec4d88e1c49' into replication
Merge branch 'replication'
Adding links to vtctld's tablet page.

Goes to the tablet's statusz and parent.
Adding a status view of topo in vtgate.
Adding and checking vtgate->vtctld links.
Removing unused parameters.
Re-organizing the mycnf flags.

Adding doc too. Privatizing methods. Long overdue.
The command line support is not here yet.
All flags are now specified in mycnf_flag.go.
Merge pull request #49 from plobsing/structured-streamlog

Structured streamlog
Supporting and using command line params in tests.
Merge branch 'master' of github.com:youtube/vitess
Merge branch 'master' into replication