Only set selinux booleans if selinux is enabled

Testing "selinux" facter fact
https://bugzilla.redhat.com/show_bug.cgi?id=892942

Change-Id: I92d4183bb6fb4f6e031ebb1b005c6fa9469b6d59
Merge "Only set selinux booleans if selinux is enabled" into folsom