WMFReplication: Make move work for a limited number of cases

Make move work not in an arbitrary case (which will require more
logic and infrastructure) but for 4 cases:

1. Move to a sibling where both instances stopped in the same coordinate
2. Move to a sibling where the master's master is stopped
3. Move to a sibling where replication is running normally
4. move to its grandfather where replication is running normally

Change-Id: Ib3642720035f9b058296b6c0ea07f9a2bf8a826c