html: deprecate ie < 10 and provide firefox link

https link to browsehappy.com (#1343)

Merge branch 'release/3.0.0'

Merge branch 'feature/documentation-and-demo' into develop

Update class utility docs

Remove white-space around browser upgrade notice

Merge branch 'feature/visual-refresh' into develop

Add file extensions back to non-helper _includes

Merge branch 'feature/refactor-layouts' into develop

Merge branch 'release/1.2.0'

Merge branch 'release/v1.1.0' into develop

Merge branch 'release/v1.1.0'

Remove Chrome Frame references