These icons are modified from a free version of IcoMoon icons:
https://github.com/Keyamoon/IcoMoon--limited-

Refer to the documentation page to learn more:
http://icomoon.io/#docs

Original package is offered under one of these two licenses: CC BY 3.0 or GPL.

http://creativecommons.org/licenses/by/3.0/
http://www.gnu.org/licenses/gpl.html

Modified icons are licensed GPL:
http://www.gnu.org/licenses/gpl.html