Add Rokkitt

Addresses issue #31
Update generated fonts page after adding Rokkitt
Switch to new branch system

Switch as mentioned in #69
Update Gemfile

Make sure Jekyll is at least 2.0.0 to support Collections
Add Muli

Suggestion from #39
Enhance meta descriptions
Add sitemap
Fix sitemap URLs
Add Lora

As per suggestion in #68
Force pulling from Brick in font specimen pages
Add Vollkorn

Also fix up Roboto names
Add in latest changes from `master`