Add missing mongodb client package on Fedora

On Fedora, when ceilometer is enabled and mongodb is used as backend,
devstack installation would fail due to missing mongodb client package.
This patch ensures the package gets installed.

Change-Id: I981bb55f86541e5ff19c52160269a7789b94423f
diff --git a/files/rpms/ceilometer-collector b/files/rpms/ceilometer-collector
index d7b7ea8..c91bac3 100644
--- a/files/rpms/ceilometer-collector
+++ b/files/rpms/ceilometer-collector
@@ -1,3 +1,4 @@
 selinux-policy-targeted
 mongodb-server
 pymongo
+mongodb # NOPRIME