Introduce a `create-initial` command for `mon` that waits for quorum

This pull request addresses the need for an easier command that will deploy all  the monitors defined in `mon initial members` and wait until they form quorum.

If/when they do form quorum `gatherkeys` will be run.

In the process a lot of useful output will be created, including JSON reports from `mon_status` and the loop status.

Every time a monitor has not formed quorum it will loop for up to 5 times with incremental waiting times.

All of these should get displayed. 

Example output (quite verbose to paste here) are commented in the actual ticket: http://tracker.ceph.com/issues/6017