Add styles for a warning icon in integrations

Review Request #8496 — Created Oct. 26, 2016 and submitted — Latest diff uploaded

Information

Djblets
release-0.10.x

Reviewers

Since integrations can now render their own statuses, it is possible
they may want to use a "warning" icon, since there are already "enabled"
and "disabled" icons. This adds the necessary LESS to use
.fa.fa-exclamation-circle as a warning icon.

Tested with rbintegrations.