RHEL6 support rpms

Install some rpms required for operation on RHEL6.  Additionally,
remove some system packages that interfere with pip installs.

Change-Id: I273ce59d7bf066e73d524f61b8ad048599101dab
diff --git a/files/rpms/glance b/files/rpms/glance
index 34e3f9a..097cf3f 100644
--- a/files/rpms/glance
+++ b/files/rpms/glance
@@ -1,3 +1,4 @@
+gcc
 libxml2-devel
 python-argparse
 python-devel