+user/location
+-------------------
+ Required:
+ user=user@bar.bz *
+
+ Description:
+ Return registered user agent locations for a given user, with
+ contact and user agent information.
+
+ Return:
+ On success, returns the array 'locations', each element contianing:
+ 'contact' is the registration contact (the location)
+ 'useragent' is the UA string from the client
+ 'expires' is the expiration time of the registration, as unix timestamp
+
+ Returns 'failed' with 'cause' = 'offline' if user is not registered ...
+ Returns 'failed' with 'cause' = 'invalid' if SIP address is malformed.
+
+ TODO:
+ Add a return code for non-existant subscriber?
+