Add validator object to 'common.js'.
Add two factor verification validation.
Fix two factor bug when updating an account.

Given account was updated with the two factor set to false.
When a different account's manage page was opened it's two factor toggle
was set to off, regardless of actual status
Fix column sorting on accounts page.

Removed computed property for accouts list.
Since 'AccountsController' is now an 'ArrayController',
it can use the Ember provided 'arrangedContent' property.
Remove forgoten 'console.log' command.