Frontend admin

## Some Front-End Javascript for the admin

### Summary

Basically I added select2.js to make the UI cleaner and added some jQuery to hide the `other` fields and show them when the 'other' option is actually selected.

### Files Changed

- layout.jade
  - Added a `block javascripts` near the end of `body`
- admin/form.jade
  - Added `select2.js` to the javascripts block
- main.js
  - Added code that activates `select2.js`
  - Added code that hides/shows the `other` fields
- styles.less
  - Added `select2.css` and `select2-bootstrap.css` to the header imports

Also added javascript/css/image files for select2

@MrMaksimize Please review and merge when you have time :smile: