Python-heatclient dependency is incorrect for stable/newton

Issues:
Fixes #82

Problem:
The python-heatclient in setup.py is pinned to 1.5.0, yet the upper
constraints file for openstack:

https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt?h=stable/newton

Pins that version to 1.5.1. We should bump to that version in this
setup.py.

Analysis:
Updated the version to 1.5.1

Tests:
Running tests against newton stack in my jenkins environment.

setup.py

@@ -34,7 +34,7 @@
                       'f5-sdk == 2.3.1',
                       'python-neutronclient == 6.0.0',
                       'python-keystoneclient == 3.5.1',
-                      'python-heatclient == 1.5.0',
+                      'python-heatclient == 1.5.1',
                       'python-glanceclient == 2.5.0',
                       'iso8601 == 0.1.11'],
     packages=['f5_os_test'],