remove Travis link

Author: stankudrow

README.rst

@@ -4,8 +4,6 @@ bson
 
 .. image:: https://img.shields.io/pypi/v/bson.svg
    :target: https://pypi.python.org/pypi/bson
-.. image:: https://img.shields.io/travis/py-bson/bson.svg
-   :target: https://travis-ci.org/py-bson/bson
 .. image:: https://img.shields.io/pypi/pyversions/bson.svg
    :target: https://github.com/py-bson/bson