Blinken's CSS should be responsive

The README has been updated to remove the screenshots, as they are no
longer accurate, and to remove attribution to the eye that is no longer
being used.

I've made:
  - the blocks on the dashboard change into a list of environments
    when using a smaller screen

  - tables in the detail view switch to being horizontally titled so
    that each cell in a row has more space e.g:

       -------------------------------
       | Title 1 | Title 2 | Title 3 |
       -------------------------------
       | Value   | Value   | Value   |
       -------------------------------

    changes to:

       -------------------
       | Title 1 | Value |
       | Title 2 | Value |
       | Title 3 | Value |
       -------------------

  - changes to the header so that rather than the all seeing eye it will
    show a link back to the home page when your in detailed view. This
    was done to save vertical space on the homepage
Merge pull request #17 from alphagov/feature/responsive-design

Blinken's CSS should be responsive