Merge pull request #214 from alphagov/bump-content

Bump the content submodule
Fix markup errors on pricing page

Problems were:
- `fieldset` tag closed twice
- fieldsets for file uploads didn't have IDs

These fixes are needed for the smoke tests to work. Not needed for go live.
Fix missing fieldset, duplicate ID on page 24
Change URL to g-cloud-6 page instead of DM login
Remove ODF format as allowed
Merge pull request #217 from alphagov/remove_odf

Remove ODF format as allowed
Prevent 500 errors if a listing id does not exist

Currently if a user tries to access a page that references a listing that does not exist in the datastore a server error occurs (due to null pointer exception).  This will instead return a 404 not found response if the listing does not exist.
Merge pull request #216 from alphagov/fix-markup-pricing-page

Fix markup errors on pricing page
Merge pull request #218 from alphagov/avoid_500s_for_null_listing

Prevent 500 errors if a listing id does not exist