Remove flashed messages from index

Flashed messages are in the base template
Redirect root URL when logged in
Add logging.basicConfig() to Sass compilation

Python complains that it has no log handlers without any kind of
logging config included.

There might be useful messages in here, like deprecation notices
or problems with the Sass compilation.
Remove compress option from scss.Scss

I can't see anywhere in the documentation that says that's a valid
option.
Correctly align navbar items

Because of a bug in pyScss, CSS selectors were getting output in the
wrong order.

Override one of those selectors in a horrible way so that our navigation
bar lines up properly.
Allow local changes to development config
Update the README to be a bit tidier
Merge pull request #17 from alphagov/list-data-sets

List data sets
Merge pull request #18 from alphagov/allow-local-development-config

Allow local changes to development config
Merge pull request #15 from alphagov/template-improvements

Template improvements
WIP