Update readme badges

Author: hardbyte

README.rst

@@ -1,7 +1,7 @@
 python-can
 ==========
 
-|release| |docs|  |build| 
+|release| |docs| |build|
 
 .. |release| image:: https://img.shields.io/pypi/v/python-can.svg
    :target: https://pypi.python.org/pypi/python-can/
@@ -11,8 +11,8 @@ python-can
    :target: http://python-can.readthedocs.org/en/latest/?badge=latest
    :alt: Documentation Status
 
-.. |build| image:: https://drone.io/github.com/hardbyte/python-can/status.png
-   :target: https://drone.io/github.com/hardbyte/python-can/latest
+.. |build| image:: https://travis-ci.org/hardbyte/python-can.svg?branch=master
+   :target: https://travis-ci.org/hardbyte/python-can
    :alt: CI Server
 
 
@@ -45,4 +45,4 @@ mailing list for development discussion.
 questions and answers tagged with ``python+can``.
 
 Wherever we interact, we strive to follow the
-`Python Community Code of Conduct <https://www.python.org/psf/codeofconduct/>`__.
+`Python Community Code of Conduct <https://www.python.org/psf/codeofconduct/>`__.