Remove skipped supporting page unit tests

The indexing tests are obsolete now that the behaviour is inherited from
Edition. The alerts tests can be added back in as part of the piece of
work which enables alerts.
Detailed guides layout fix

Fixes due to changes when Elliot changed document_page class to
document-page.

https://www.pivotaltracker.com/story/show/61460612
Merge pull request #1092 from alphagov/detailed-guides-layout-fix

https://www.pivotaltracker.com/story/show/61460612

Detailed guides layout fix
Merge pull request #1089 from alphagov/remove-skipped-tests

Remove skipped supporting page unit tests