added the wb-inv class back in the span elements taken out of #570
Merge pull request #576 from shawnthompson/features

added the wb-inv class back in the span elements taken out of #570
Build: Don't re-minify core files

Allows IE8 minifacation fixes to bubble up
Merge pull request #580 from nschonni/dont-reminify-core

Build: Don't re-minify core files