Update URL to epel rpm package

A new version was put on the epel repository, it is 7-1 now.

(cherry picked from commit 5a967de9fbd92529fab572e5d28f52c60d5bebf3)

Conflicts:
	stack.sh
shouldn't the URL be

http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-1.noarch.rpm

and not the beta?