Add initial index html and login procedure

- Add initial HTML to the index page for the admin and timetable tenant
    - Header
    - Sub header
    - Sidebar
    - Content
- Add a login form to the header and enable signing in and out
- Get the `/me` data when the page is initialising
- Create a `renderTemplate` function that takes a template, data and a target as arguments
- CasperJS and Qunit tests for the above
I wonder if we should add the other hosts as well for future testing (e.g. 2013.timetable.cam.ac.uk)? And the other tenants (Oxford)?