Add requirements file for travis

In order to install httmock.

Author: d-sparks

.travis.yml

@@ -2,4 +2,6 @@ language: python
 python:
   - "2.6"
   - "2.7"
-script: python ./test/test_clever.py
+script:
+  - pip install -r ./test/requirements.txt
+  - python ./test/test_clever.py

test/requirements.txt

@@ -0,0 +1 @@
+httmock

test/test_clever.py

@@ -149,7 +149,8 @@ def test_rate_limiter(self):
           functional_test({"api_key": "DEMO_KEY"}),
           functional_test({"token": "7f76343d50b9e956138169e8cbb4630bb887b18"}),
           AuthenticationErrorTest,
-          InvalidRequestErrorTest]:
+          InvalidRequestErrorTest,
+          TooManyRequestsErrorTest]:
     suite.addTest(unittest.TestLoader().loadTestsFromTestCase(TestClass))
   unittest.TextTestRunner(verbosity=2).run(suite)