Alphabetise requirements

because pedantry
Merge pull request #43 from alphagov/sort-requirements

Alphabetise requirements
Change tests for new template
Respond to henry's comments about the template
Tests for new get_authorization_url method taken out of login

root will will now redirect to the url given by this
Remove login route. root now redirects here if the user has no session.

To try again when a user has the permission they will have to sign out
and sign in again. If this becomes a problem we can readd a hidden
/login route or cause the app /sign_out root to only clear the session
and not log the user out of signon. Then revisiting the app root will
correctly log them in.
test for redirect to authorization url

also remove old comment
redirect to authorization url when no session - tests pass
Merge pull request #44 from alphagov/nice-page-when-no-signin-permission

Nice page when no signin permission