implement startup loading events (bug 1024014)
Merge pull request #490 from ngokevin/perfevents

implement startup loading events (bug 1024014)
update yulelog icons and pngquant icons (bug 1025299)
move nunjucks globals to helpers_local
Merge pull request #492 from cvan/yulelog-icons

update yulelog icons and pngquant icons (bug 1025299)
use apps iframe for installs/launch (bug 1029687)