Discover config file for mongodb

mongodb 2.6 uses diff config file as opposed to
lower versions. Given diff file candidates code
selects config file that is available

Change-Id: I8fe9eea39a47aa890834a0c55e98c062f9b9fd15
Closes-Bug: #1368468
Mandate detach replicas before deleting replica source

If the user attempts to delete an instance which has
replicas attached to it, forbid the delete.

Closes bug: #1362299

Change-Id: I644243aef74d9a34b7726139f9fa5ca8bdb1452c
Merge "Discover config file for mongodb"
Merge "Mandate detach replicas before deleting replica source"