[WIP] Added a Replicator object

This is a work in progress for the Replicator object. It can successfully create a replication -- next steps are to fill out and test the stubs for getting replication status, getting all replications, etc.

Would like some feedback to verify that I'm going in the right direction with this, though.

@ksnavely @evansde77 @jcounts @dmannarino 
probably worth outlining what we would like to see happen and running it by Rob. 

We can probably do stuff like generate an api key for replications on the fly, rather than posting the user/pass combination.