Converting DrupalMessageTest to a unit test.
Merge pull request #75 from fubhy/drupal-message-action

Converting DrupalMessageTest to a unit test.
Fixing typos and copy&paste screw ups.
Moved provided context to its own interface.
Added ProvidedContextTrait and also use it in rules actions now.
Create a more generic Rules context trait also for context mapping.
Map context in the Rules action expression.