Collection synonyms

Please add internal support for database collection synonyms. Similar to Oracle synonyms or from a file system perspective Unix symbolic links or from a network perspective c-names.

Basically just allow us to internally define secondary names for any given collection in any database.

This would ease transition of data versions and creates a simple work around for the problem of not being allowed rename sharded collections.

For example all the code could access the "data" as if it were a collection however the actual collection names would be "data_v1", "data_v2" etc where the synonym "data" points whichever is the current set.