Don't exclude test files from PEP8

We're hand-writing them so I don't see a reason to exclude these.
Merge pull request #26 from alphagov/dont-exclude-pep8-for-tests

Don't exclude test files from PEP8
Refactor code to filter kwargs into function

This just makes the code slightly easier to read.
Merge pull request #29 from alphagov/improve-admin-handler

Admin handler which makes exceptions pretty
Adding comment about query string params in urls
Move JSON serializing code to libs and added tests

It makes sense to move this code into a library function to aid reuse.
Move views into their own directory

This mirrors the structure used in models and admin.
Merge pull request #31 from alphagov/refactor-data-set-json-endpoints

Refactor data set json endpoints