Make sure that the currently-set language is the
one that shows on the left sidebar if no language
preference exists.

ECOM-135
BLD-1226: enable 'delete_inactive_group' test.
Merge pull request #4970 from edx/anton/enable-bok-choy-test

Enable Bok Choy split test.
Merge pull request #4959 from edx/diana/set-cur-lang

Make sure that the currently-set language is the one that shows on the left sidebar if no language  preference exists.
Replace reference to Google OpenSans with edX-hosted OpenSans
Addressed comments.
Fixed path to font files.
Use Bourbon mixin utility instead.
Ordered font declarations by increasing font-weight
Fixed wrong path to one font file.