Work on .board class & home page

- Separate .board into own .less file
- Fix .board work better on narrow screens
- Remove carousel from home and use .board instead
- Remove unused images
- Clean out front page html/js/less code
User model: require unique email & fix default languages
Fix mini profile fields
Improve password reset visuals
Move docs to the wiki https://github.com/Trustroots/trustroots/wiki
New about page, beta notification for homepage