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Add ability to auto-create replica set

This really should only be done in dev environments -- typically a data recovery
would be done prior to fully enabling the replica set and adding the indexes.

However, for ease of use in dev and vagrant environments, we just want to have mongo
working from the get-go.
Add a delay option to mongo_initiate_replica_set

Since the replica set can take a while to set up, particularly if
adding secondary nodes to a populated database, add a optional
delay.

This makes it a bit easier to ensure that the replica is set up
before moving ahead in automated solutions.
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