Fix the background image on mobile devices.

The background image had width: 100%, which refers to the initial view port.
When zoomed out, this is less than the width of the content pane (970px).

By adding min-width:970px to the background and the background-city, this
problem can be solved.
Added .travis.yml and a settings file for tests
Merge branch 'travis'

* travis:
  Added .travis.yml and a settings file for tests