Allow setting of local_government in admin

This flag currently only applies to news/speeches.
Integrate local government filter into announcements
OCD changes to indentation and JS
Highlight local government selection
Tidy up wording and styles for checkbox
Add rel=external to external mainstream links
Merge pull request #189 from alphagov/local-government-announcements

Filtering of local government announcements
Merge pull request #191 from alphagov/external-mainstream-links

Add rel=external to external mainstream links
Bold for page titles

first step adding bold to the site - adding it to page headings and the
big numbers on homepage and 'how gov works'
Fix broken build