Update badges

Author: tony

README.rst

@@ -1,14 +1,16 @@
 tmuxp, a novel approach to manage `tmux(1)`_ (>= 1.8) workspaces through
 `python objects`_, JSON or YAML.
 
-.. image:: https://badge.fury.io/py/tmuxp.png
+.. image:: https://img.shields.io/pypi/v/tmuxp.svg
     :target: http://badge.fury.io/py/tmuxp
 
-.. image:: https://travis-ci.org/tony/tmuxp.png?branch=master
+.. image:: https://img.shields.io/travis/tony/tmuxp.svg
    :target: https://travis-ci.org/tony/tmuxp
 
-.. image:: https://coveralls.io/repos/tony/tmuxp/badge.png?branch=master
+.. image:: https://img.shields.io/coveralls/tony/tmuxp.svg
     :target: https://coveralls.io/r/tony/tmuxp?branch=master
+    
+.. image:: https://img.shields.io/github/license/tony/tmuxp.svg
 
 .. image:: https://raw.github.com/tony/tmuxp/master/doc/_static/tmuxp-dev-screenshot.png
     :scale: 100%