Add python-ceilometerclient in requirements

With the addition of the ceilometer client in the scenario tests, the
python-ceilometerclient is missing. This patch adds it to the packages
to be installed in requirements.txt.

Change-Id: Icb667def3afb71d20bc7a90e6e031cf671adc321
Closes-Bug: #1337309
diff --git a/requirements.txt b/requirements.txt
index ab2903a..b86d179 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,6 +7,7 @@
 boto>=2.12.0,!=2.13.0
 paramiko>=1.13.0
 netaddr>=0.7.6
+python-ceilometerclient>=1.0.6
 python-glanceclient>=0.9.0
 python-keystoneclient>=0.9.0
 python-novaclient>=2.17.0