core: getProfileName no raise ProfileUnknownError + minor doc fixes

src/memory/memory.py

@@ -361,6 +361,7 @@ class Memory(object):
         @param profile_key: can be the profile name or a keywork (like @DEFAULT@)
         @param return_profile_keys: if True, return unmanaged profile keys (like "@ALL@"). This keys must be managed by the caller
         @return: requested profile name or emptry string if it doesn't exist
+        @raise exceptions.ProfileUnknownError if profile doesn't exists
         """
         return self.params.getProfileName(profile_key, return_profile_keys)