Numpy is required for tests now, due to nilmdb.client.numpyclient

Still allow installation without it, though.

setup.py

@@ -107,6 +107,7 @@ setup(name='nilmdb',
       author_email = 'jim@jtan.com',
       tests_require = [ 'nose',
                         'coverage',
+                        'numpy',
                         ],
       setup_requires = [ 'distribute',
                          ],