Email Settings refactoring and bug fixes

- Various bug fixes for email settings and event states (#286 and #287)
- Email Subjects now mandatory if send mail is enabled
- Load Default template feature implemented (#16)

![Default template](http://s1.directupload.net/images/140720/gv7u9tie.png)
Why don't you load @event in an before_action? The this is covered for all the controller actions that need @event