re-structure the couchbeam, to handle each CouchDB API via gen_server call,
By the CouchDB API Spec, http://wiki.apache.org/couchdb/Complete_HTTP_API_Reference
Compose the following gen_server module,
1) couch_api_auth
2) couch_api_db
3) couch_api_doc
4) couch_api_search
5) couch_api_server
6) couch_api_view