Disable selinux for RHEL6

selinux locks down httpd which causes various issues for Horizon
working from git checkouts.  Dealing with selinux is more a deployment
than a development issue, so we just disable it for devstack.

Change-Id: I1e61f34e812360dafacd3b3288e66bc9cc5f1648
Fixes: 1175444
diff --git a/stack.sh b/stack.sh
index 5a6945d..e5b2b27 100755
--- a/stack.sh
+++ b/stack.sh
@@ -560,6 +560,10 @@
 # ============================
 
 if [[ is_fedora && $DISTRO =~ (rhel6) ]]; then
+    # Avoid having to configure selinux to allow things like httpd to
+    # access horizion files or run binaries like nodejs (LP#1175444)
+    sudo setenforce 0
+
     # An old version (2.0.1) of python-crypto is probably installed on
     # a fresh system, via the dependency chain
     # cas->python-paramiko->python-crypto (related to anaconda).