Change conversion funnel to use Mon -> Sun weeks

@moonpxi
@gtrogers
Fix test descriptions.
Increasing capybara wait time on travis

Tests were timing out on travis, worth checking if
it's more to do with random ordering than timeouts
but this should fix it for now.
Merge pull request #125 from alphagov/use-Mon-to-Sun-weeks

Once again failing due to flaky feature tests despite bumping timeout. Should pass on jenkins so merging.