Heat rpm spec needs to honor usr_only

When smithy is invoked with "-u", the usr_only flag is not being checked
by the openstack-heat RPM spec file and as a result, installs all the
files, rather than just the ones in /usr.

Change-Id: I13333bb9622d6dc3e7f8d93edb6ce2fa8012a1bb
Merge "Heat rpm spec needs to honor usr_only"