Copr now using Fedora 21 for builder instances

[Valentin Gologuzov]

Hi,

Today we have moved copr builders to Fedora 21,
rawhide builds should be fine again.

If you encounter some new problem, please inform us at copr-devel@ ML
or at irc: #fedora-buildsys

-- 
Best regards,
Gologuzov Valentin.