refs #4993, #5073
- Removed nonexistent helpers siteDescription and bodyClass from admin templates
- Changed password.hbs to private.hbs to match the route name
- added a new input_password helper for rendering the password input with the correct properties
- removed the forward input as this can be handled via urls only
- moved 'private' to routeKeywords
- added 'private' context
- minor update to text next to the password in settings
