Adding unittests (#300)

* Create a custom class to handle aborting 204 properly.  If this isn't
covered the server will send a 500 due to a python exception

* Moved py.test configuration under tool:pytest, this was causing a
warning.  This is new to 3.0.1 which is now the pinned version

* Unittest for puppetboard.utils

requirements-test.txt

@@ -1,6 +1,8 @@
 pep8==1.6.2
 coverage==4.0
 mock==1.3.0
+pytest==3.0.1
 pytest-pep8==1.0.5
 pytest-cov==2.2.1
 cov-core==1.15.0
+unittest2==1.1.0; python_version < '2.7'