remove rebar.config.script, handle deps via rebar.config

Finally remov ethis ugly hack from apache couchdb and make applications
really independant so we can eventually ship without the map/reduce and
such things.

note: to be totally independant couch_changes_http with view changes should be moved to
its own application. Also we should make sure to move all couchapp calls
in couch_query_server in their own app.