OF10ActionsSerializer and OF13ActionsSerializer split into separate actions (to allow easier action extensibility)
 - OF13MatchEntriesRegistryHelper renamed to EnhancedKeyRegistryHelper
   + used also in ActionsInitializer
 - added serializeActions into CodingUtils
 - created static ActionConstants class

Signed-off-by: Michal Polkorab <michal.polkorab@pantheon.sk>
Change-Id: I61b11f3acf8d961757e3753a40d26cb77dc02615