Don't index Whitehall content
Whitehall artefact form
Add tests for existing functionality
Only redirect to publisher for publisher items
Use a released version of govuk_content_models
Use text instead of an icon for format

This lets us show something meaningful for Inside Government formats, without
needing to design icons just for this purpose, or making the column a mixture
of text and icons.

Speaking with Jon Sanger, the icons are useful in Publisher, as they allow
quick scanning of lists (eg "I can ignore all these because they're licences"),
but not so important in Panopticon.
Remove defunct Whitehall format icons
Reinstate language icon
Update index exclusion list

There is no longer a format of inside_government, and the list of whitehall
formats is longer and will grow over time.
Only activate the nav link for the current form.

Since we have two forms from the same controller action - one for new
artefacts, one for Whitehall artefacts - the previous way of
highlighting nav links would highlight both links if either was active.
Merge pull request #59 from alphagov/whitehall_support2

Whitehall support