Adding badge for python versions

Author: nicoddemus

README.rst

@@ -15,20 +15,25 @@ of a test:
         UnixFS.rm('file')
         os.remove.assert_called_once_with('file')
         
-|version| |downloads| |ci| |coverage|
 
-.. |version| image:: http://img.shields.io/pypi/v/pytest-mock.png
+|python| |version| |downloads| |ci| |coverage|
+
+.. |version| image:: http://img.shields.io/pypi/v/pytest-mock.svg
   :target: https://crate.io/packages/pytest-mock
 
-.. |downloads| image:: http://img.shields.io/pypi/dm/pytest-mock.png
+.. |downloads| image:: http://img.shields.io/pypi/dm/pytest-mock.svg
   :target: https://crate.io/packages/pytest-mock
 
-.. |ci| image:: http://img.shields.io/travis/nicoddemus/pytest-mock.png
+.. |ci| image:: http://img.shields.io/travis/nicoddemus/pytest-mock.svg
   :target: https://travis-ci.org/nicoddemus/pytest-mock
 
-.. |coverage| image:: http://img.shields.io/coveralls/nicoddemus/pytest-mock.png
+.. |coverage| image:: http://img.shields.io/coveralls/nicoddemus/pytest-mock.svg
   :target: https://coveralls.io/r/nicoddemus/pytest-mock
 
+.. |python| image:: https://pypip.in/py_versions/pytest-mock/badge.svg
+    :target: https://pypi.python.org/pypi/pytest-mock/
+    :alt: Supported Python versions
+
 
 Usage
 =====