[Forward port to Utilities-3.1] - ResourceServlet logs warning about .woff2 files

When opening the channel manager, a warning about .woff2 files is logged.

Steps to reproduce:
1. login to the CMS
2. open a channel

Expected: no warnings are logged
Actual: the following warning is logged:
WARN [org.onehippo.cms7.utilities.servlet.ResourceServlet.prepareResponse():428] No mime-type mapping for resource path: *****.woff2. Fallback to 'application/octet-stream'.