Make couchdb a plugable backend
Fix failing tests
Change database deletion method
Adapt tests to the new backend system
Rename daybed.backends.couch_bd -> daybed.backends.couchdb
Rename daybed.backends.couchdb.Backend -> daybed.backends.couchdb.CouchDBBackend
Namespace backend related configuration
Merge pull request #49 from AntoineCezar/issue_42

Solve Issue 42