fix zadmin featured apps when no category given
Merge pull request #915 from ngokevin/fixfeatured

fix zadmin featured apps when no category given
do not expect request.TABLET/request.MOBILE in context_processors (for @ngokevin <3)
remove unused helper function in theme test views
try un-SkipTesting theme updatecheck tests (bug 860476)
try to optimize edit theme form (bug 855619)
Merge pull request #914 from ngokevin/perfedittheme

try to optimize edit theme form (bug 855619)
reflect @cvan's context_processor fix
refactor category save on theme edit, don't spawn reupload task every time
redirect users after accepting TOS from developer API page (bug 860111)
Added HTML receipts (bug 890046)