Misc: Drop support for older browsers; update support comments

That includes IE<8, Opera 12.x, Firefox<29, Safari<6.0 and some hacks
for old Blackberry.

Fixes gh-1836
Fixes gh-1701
Refs gh-1815
Refs gh-1820
@timmywil made me aware that we're firing `jQuery.ready.promise()` manually on `master` and we're not doing that here. It used to work since we had a couple of unit tests run on DOM ready but now they're all gone so it started breaking. Fixed!