fix "Loading..." title for "Oh no!" detail page (bug 8451386)

https://bugzilla.mozilla.org/show_bug.cgi?id=1035005

see PR #503 for alternative approach
I merged in some galaxy code into Commonplace where the fragment_load_failed event is supplied the whole context.

https://github.com/mozilla/commonplace/commit/c00b2d98971a851dbcf9cfbd9e8efd2d3fcbb769