Add edit motion notifications for users who have voted

This also adds edit proposal functionality with revision history

This feature provides the ability to edit a proposal and notify all the members who have voted on the motion

- Remove edit closed date form routes and code
- Re-implement motion CRUD edit/update functionality
- Create a revision history page and functionality using paper_trail
- Remove ability to select a previous date on date picker
- Rework close date validations to not allow out of range dates.  eg. 32/13/2073548235
- Move date validation code to validations.js.coffee module
- Add edit_message field to motion form
- Add js to hide/show edit_message field
- Add Event
- Add Discussion Item
- Add Notification Item
- Add MotionMailer method
- Add text and html email templates