Added get_db for those that wish to fail if a database doesn't exists and cleaned up redundant code.
Added get_db for those that wish to fail if a database doesn't exists and cleaned up redundant code.

ghickman/couchdbkit,ghickman/couchdbkit,benoitc/couchdbkit,benoitc/couchdbkit,benoitc/couchdbkit,ghickman/couchdbkit