Add ipython on the development role
Merge pull request #583 from alphagov/ipython-development

Add ipython on the development role
Use nginx version from our PPA everywhere

* remove nginx Apt repo so that later versions aren't installed
* use our version (from ubuntu repo)

This is preparatory work so that we can use nginx-extra and thus use
lua/Perl to do stuff.
Merge pull request #584 from alphagov/feature/consistent-nginx-version

Use nginx version from our PPA everywhere