Travis: reorder packages to install

Author: Clement Champetier

.travis.yml

@@ -80,7 +80,9 @@ addons:
     - swig
     - libboost1.55-all-dev
     - python-dev
+    - python-imaging
     - python-numpy
+    - python-nose
     - python3-dev
     - python3-nose
     - libfreetype6-dev
@@ -97,8 +99,6 @@ addons:
     - libglew-dev
     - libgraphviz-dev
     - graphviz-dev
-    - python-nose
-    - python-imaging
     - libopenjpeg-dev
     - libturbojpeg
     - libxmu-dev