Precompile assets prior to building tarball

https://bugzilla.redhat.com/show_bug.cgi?id=1121202
@brandondunne This is needed by both centos and rhel appliance builds, whereas the tarball creation is only run in rhel builds as part of the source tarball in the rpm.  Therefore, we need to compile assets here.

What happens if we leave this in cfme-setup.sh but also precompile them as part of the tarball creation?  Shouldn't this call in cfme-setup.sh be a no-op?

What was the exact error that was occurring that we're solving here?