Adding a /healthz url to vttablet.

It reflects the last result of the health check.
Adding integration tests to confirm it's wired up properly.
Adding a health check for query service in the right state.

CHanging the health check interface to pass a flag indicating
if QS should be running or not.
Now checking tabletserver.IsHealthy in health check.
Fixing health links in vttablet status page.
Make VitessInputFormat accept sql query

Deprecate use of table name as MapReduce input and let VitessInputFormat
support any valid select query and use the result as input instead.
Merge pull request #208 from yaoshengzhe/fix_VitessInputFormat_accept_sql

Fix vitess input format accept sql
Adding a FindAllShardsInKeyspace command to vtctl,
for debugging purposes.
Changing the display of the status report for vt worker.
Merge branch 'master' into replication
Merge pull request #231 from youtube/resharding

Resharding
Merge pull request #232 from youtube/replication

Replication
Changing ok message for health check.