updated button with SVG version

Author: fermayo

README.md

@@ -1,6 +1,6 @@
 ## quickstart-python
 
-[![Deploy to Tutum](https://s.tutum.co/deploy-to-tutum.png)](https://dashboard.tutum.co/stack/deploy/)
+[![Deploy to Tutum](https://s.tutum.co/deploy-to-tutum.svg)](https://dashboard.tutum.co/stack/deploy/)
 
 A simple Python app (using Flask) which can easily be deployed to Tutum.