Add couch_debug:opened_files_by_regexp/1
Add couch_debug:opened_files_by_regexp/1

couch_debug:opened_files_by_regexp is an efficient way to find out list
of file descriptors or couch_file processes which path matches given
regexp

fkaempfer/couchdb,fkaempfer/couchdb,cloudant/couchdb-couch,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,apache/couchdb-couch,apache/couchdb-couch,cloudant/couchdb-couch,cloudant/couchdb-couch,fkaempfer/couchdb,apache/couchdb-couch