Use svg for travis instead of png.

Author: haesbaert

README.md

@@ -2,7 +2,7 @@
 
 A portable library to read and write raw packets.
 
-[![Build Status](https://travis-ci.org/haesbaert/rawlink.png)](https://travis-ci.org/haesbaert/rawlink)
+[![Build Status](https://travis-ci.org/haesbaert/rawlink.svg)](https://travis-ci.org/haesbaert/rawlink)
 
 Rawlink is an ocaml library for sending and receiving raw packets at the link
 layer level. Sometimes you need to have full control of the packet, including