update travis

.travis.yml

@@ -9,16 +9,10 @@ addons:
       - build-dep 
       - python-pygame
       - mercurial
-      - libav-tools 
-      - libsdl-image1.2-dev 
-      - libsdl-mixer1.2-dev 
-      - libsdl-ttf2.0-dev 
-      - libsmpeg-dev 
-      - libsdl1.2-dev 
-      - libportmidi-dev 
-      - libswscale-dev 
-      - libavformat-dev 
-      - libavcodec-dev
+      - libsdl2-dev
+      - libsdl-image1.2-dev
+      - libsdl-ttf2.0-dev
+      - libsdl-mixer1.2-dev
 install:
   # We do this conditionally because it saves us some downloading if the
   # version is the same.