Tests/Tox/TravisCI improvements

CONTRIBUTING.rst

@@ -44,7 +44,7 @@ General Guidelines
 - Avoid backward breaking changes if at all possible.
 - Write inline documentation for new classes and methods.
 - Write tests and make sure they pass (make sure you have a mongod
-  running on the default port, then execute ``python setup.py test``
+  running on the default port, then execute ``python setup.py nosetests``
   from the cmd line to run the test suite).
 - Ensure tests pass on every Python and PyMongo versions.
   You can test on these versions locally by executing ``tox``