Messed with the jade, improved site authentication.

landing.controller
  Removed a user authentication check -- these are now done at a higher level.
profile.controller
  Fixed an issue when rendering achievements.
route.controller
  Added an authentication function to lock out parts of the site that require login.
server.js
  Added screening to various routes that require login.
404.jade
  Added alert
500.jade
  Added alert
layout.jade
  Added authentication error check
profile.achievements.jade
  Bugfix.
profile.progress.jade
  Bugfix.