cherry-pick 5e36816a783b6212e8cd7d0374fe6aea76ca7816 -  Fix Merge conflicts - And copy the changes onto error layout page too.

Fix #1318 by adding attribution for FontAwesome

Conflicts:
	src/NuGetGallery/Views/Shared/Layout.cshtml
make CancelPendingCommits [Authorize] so that people will be more likely to be logged in before they submit the form.