Replicasets configuration fixes and some small small tweaks around error handling and displaying

I've made 4 separate commits to fix the following issues:
* The 3rd replica could not be added to a sharded replica set, because the previous nodes have already been initiated.
* Error display fix (not hiding and Exception when it occurs)
* Error checking fixes (errmsg should be checked for error not the full result)
* Added an attribute to specify the wait for the mongod instance to start at the first time to be able to handle preallocation lag