Removing all dynamic pages from the manifest.

Dynamic pages are put into the manifest when a user visits the page and there is a 'manifest=' attribute in the <html> tag
Only including manifest on home and submit pages

...as these are the only pages we want to be available offline
Making use of manifesto filters to trim the manifest size down from >300 to about 80
Merge pull request #32 from adapt/feature/manifest-fixes

Fixes to the manifest and offlining