This change does not affect distribution but simply separates the two
concepts of connection ID (ip:port pair) and alias (value set via the
"alias" connection parameter), the method getConnectionByAlias() has
been added to reflect this change.
The method getConnectionBySlot() has also been added.
In addition to that, the methods askSlotsMap() and buildSlotsMap() of
the redis-cluster connection backend have been renamed respectively
to askSlotMap() and buildSlotMap().