feat(review-board): add review board support

[KattMingMing]

This PR changes:

• Uses codeintellify to add support for Review Board.

Testing plan:

I have tested on:

• [x] Chrome
• [x] Firefox
• [ ] Safari
• [ ] Phabricator Bundle

[chrismwendt]

Here's how to move this PR to https://github.com/sourcegraph/sourcegraph/tree/master/packages/browser-extensions

cd browser-extensions
git format-patch master --stdout > /tmp/patch

cd ../sourcegraph
cat /tmp/patch | git am -3 --directory=packages/browser-extensions/
# and fixup merge conflicts