provide a FOSS license

Hey I'm really excited about this extension after hearing about it on @Flancian's Twittter feed. There's currently no license file for this project though, which means it's defaulted to a restrictive "all rights reserved" copyright license (see screenshot) so I was hoping you could post one – hopefully one that's open source (ie: not just "source available"). Github provides a great brief guide to choosing a license Thanks for your time and this extension!