Add IE9-specific stylesheet
Remove fancy select styling for IE <= 9 on stats announcement filter

The select dropdown arrows can't be hidden without some serious hackery
in IE9 and can't be hidden at all in IE <= 8. It's better to strip back
any fancy styling for IE.
Use same styling for publication & stats announcement filters

Previously, the styling for the publication filter and stats announcement
filter were using two different versions of similar css. This modifies the
publications filter to use the more generic filter-form-block css helper.
Merge pull request #1577 from alphagov/fix-selects-in-ie

Fix selects in ie

Story: https://www.pivotaltracker.com/story/show/73412800

Previously, select boxes on the frontend filters were displaying with two down arrows - one from the background image, and one browser-rendered dropdown arrow. This PR strips out the more complicated select styling for IE version <= 9.

I needed to introduce an IE9 stylesheet to achieve this.

This PR also rationalises the styling between the publications filter and the stats announcement filter.
Consolidate styling for document filters

Although The Stats announcement filter shared a lot of
styling with the other document filters, it didn't share
all of it. This consolidates the styling of all the document
filters so they are all using the same CSS.
Strip superfluous markup from document filters

The document filter markup seems to have grown over
time. This removes most of the extra no-longer-needed
tags, classes and ids. This also brings the document
filter markup more inline with the stats announcement
markup.
Dry up some filter form markup
Add ability for LinkChecker to check authed links

Because the preview environment is hidden behind HTTP basic auth, link
checking will fail for any links to other pages on the site in this
environment. This change allows us to configure domains that require
authentication such that the LinkChecker will be able to automatically
apply the auth credentials when required. This will be configured at
deploy time so that environment-specific details are kept out of the
codebase.
Merge pull request #1586 from alphagov/allow-authed-domains-to-be-link-checked

Add ability for LinkChecker to check authed links
Merge pull request #1585 from alphagov/consolidate-document-filter-styling

Consolidate document filter styling
Style corp information page language links

This extracts the styling for .available-languages into
a css helper, taking it out of the heading scope.
Always render using html fractions partial
Merge pull request #1589 from alphagov/fix_fractions_in_atom_feeds

Fix atom feed where fractions are present in a publication
Merge pull request #1588 from alphagov/fix-translation-links-on-corp-info-page

Style corp information page language links
Add new Whitehall::BrokenLinkReporter

This version runs a LinksReport for each public edition and generates
CSV files listing those editions that have broken links, organised by
their lead organisation.
Cleanup old BadLinkReporter code
Update language around broken links

The notifier is sending "broken link" reports not "bad link" reports.
Rake task to generate/send broken link reports
Handle documents with no lead organisation

A Speech that has a person_override set do not have to have a lead
organisation. This updates the BrokenLinkReporter to handle this,
falling back to the first organisation available.
Handle documents with no organisations

It's technically possible for a document to be associated with no
organisations. This handles that case, putting the results from the
broken link checks into a separate CSV file.