Switch to couch_log
Ask couch_httpd:log_request not to log a duplicate line
Change API to function per level
Use couch_mrview for view logic and callbacks

This updates the various view functions to use couch_mrview utility
functions, and removes a large amount of the view utility functions
that are better served by couch_mrview. It also uses the view
callbacks from couch_mrview, removing even more logic from this
module.
Update _all_dbs to use couch_mrview
Update chttpd show and list functions to use couch_mrview
Switch to using couch_mrview for the chttpd design info endpoint

This also standardizes the output of design info to use the format
from CouchDB. In particular, this outputs {"name","foo"} as CouchDB
currently does, rather than the {"name","_design/foo"} that it did
previously.