Fixes failing tests introduced in pull request #824

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off.

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off. Also, the faux SHA1 cannot have underscores or
it will not match the commit pattern defined in the routes.

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off.

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off.

#changed_merge_request_email was really sending emails about merge
request reassignments. Updated method name to reflect that.

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off.

#changed_issue_email was really sending emails about issue reassignments.
Updated method name to reflect that.

Update method to take ids and then perform #finds itself during mailer
queue worker kick-off.

Covers new user, new issue and wall note emails.

Depends on email_spec (https://github.com/bmabey/email-spec/) for
friendly matchers.