Central server contact / user registration / landing page / menubar redesign

This checkin depends on the (currently outstanding) "urls" pull request.

New features:
* A contact form "wizard" that:
  - Displays relevant documentation based on user issue
  - Gathers relevant information and saves it to the central server database
  - Sends email out to the proper issue-tracking system

* User registrations that:
  - Allow opting in to our MailChimp newsletter
  - Asks for organization name (allows entering more org info optionally)
  - Creates an organization and (default) zone when the user is created
  - ** YES, all users now have organizations and zones created for them! :dancer: 

* Menubar now has important links:
  - Install and Contact added
  - Sign up removed (this only should be done through the installation or local-server registration pathways)
  - About us added, with a link to learningequality.org

* Landing page has been reconfigured
  - Condensed methods for contact
  - Clear focus on our basic message
  - Actions become cleaner and clearer