Add specs for Notify ActionMailer emails.

Covers new user, new issue and wall note emails.

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

spec/spec_helper.rb

@@ -11,6 +11,7 @@ require 'capybara/dsl'
 require 'webmock/rspec'
 require 'factories'
 require 'monkeypatch'
+require 'email_spec'
 
 # Requires supporting ruby files with custom matchers and macros, etc,
 # in spec/support/ and its subdirectories.