DAR-1405 Avoiding count on master

* changed the query to only ask for recent revisions
* stored the information that the email was sent to avoid repeating those queries
* prepared the test skeleton
* removed unused method from Masthead
DAR-1405 Code review changes
DAR-1405 Adding implementation for unit test
DAR-1405 Updated unit tests for readability
DAR-1405 Changes to unit tests after code review, additional test
DAR-1405 Additional changes to unit test after code review
DAR-1405 SQLreview change, removing unnecessary ORDER BY
DAR-1405

Added handling of hourly throttle and sending of next edit emails
that were lost in the original fix
Updated unit tests
Merge pull request #1569 from Wikia/DAR-1405

DAR-1405 Avoiding count on master