Added script to set up replication in CouchDB

This script set up replication between a source and a destination CouchDB instance.

The reason to put the _security attribute separately from the rest of the database content is that this is a special document that cannot be replicated in a standard way. Cite from [here](http://wiki.apache.org/couchdb/Security_Features_Overview#Authorization):

>Note that security objects are not regular versioned documents (that is, they are not under MVCC rules). This is a design choice to speedup authorization checks