fixes #2573 - refresh Fedora 18 comps, don't force SCL
fixes #2106, #2123, #2561 - sign RPMs, rename -ec2 to -compute, fix foreman.repo URLs
fixes #2555, #2560 - add foreman-release and MySQL gems to comps
Merge remote-tracking branch 'domcleal/rpms' into develop

* domcleal/rpms:
  fixes #2555, #2560 - add foreman-release and MySQL gems to comps
  fixes #2106, #2123, #2561 - sign RPMs, rename -ec2 to -compute, fix foreman.repo URLs
  fixes #2573 - refresh Fedora 18 comps, don't force SCL