add travis badge

Author: bubenkoff

README.rst

@@ -7,6 +7,8 @@ scales to support complex functional testing.
 
 .. image:: https://coveralls.io/repos/pytest-dev/pytest/badge.png?branch=master
    :target: https://coveralls.io/r/pytest-dev/pytest
+.. image:: https://travis-ci.org/pytest-dev/pytest.svg?branch=master
+    :target: https://travis-ci.org/pytest-dev/pytest
 .. image:: https://pypip.in/v/pytest/badge.png
    :target: https://pypi.python.org/pypi/pytest
 
@@ -16,8 +18,6 @@ Changelog: http://pytest.org/latest/changelog.html
 
 Issues: https://github.com/pytest-dev/pytest/issues
 
-CI: https://drone.io/bitbucket.org/pytest-dev/pytest
-
 Features
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