+user/change_pw?user=foo@bar.bz&password=baz
+ Changes the password for the given user, returns 'ok' with 'detail' as
+ a descriptive text on success. In the current implementation,
+ provisioning and kamailio passwords are handled separately, so one
+ may succeed and the other fail. As is, this permits password changes
+ of non-local provision users with minimal effort.
+
+ Returns 'failed' with 'cause' = 'nonexistant' if user does not exist.
+
+ Returns 'failed' with 'cause' = 'dbfail' if the database request
+ failed. Note that this may be because the given password was identical
+ to the old.