ActionComplete / ActionFailed called after Action completion

Addressed further points in PR 617:
 - Action results no longer a pointer, thus no nil checks needed
 - ActionFail call-home now sends a sane message to the user, without
   discarding error context
 - Minor tweaks to relation write-out logic
 - Removed pointless actionStatus type
 - Checks for nil state handle for ActionComplete / ActionFail