Merge branch 'event_to_trigger' of https://github.com/CiviCooP/org.civicoop.civirules into event_to_trigger

added logging to the Action and Condition classes and implemented a basic psr3 log interface and log level class

errors during claiming next item, refactored so that next item is the one with the oldest release time

issue with group contact cache resulted in a deadlock whilst checking a condition. Refactored checking of group membership so that the group contact cache is not used