Fix fork skimage

.travis.yml

@@ -11,6 +11,7 @@ before_install:
 install:
   - sudo -H apt-get install -qq -y pyqt4-dev-tools
   - sudo -H apt-get install -qq -y python-qt4
+  - sudo -H apt-get install -qq -y python-numpy  # for skimage
   - sudo -H python setup.py install
 
 script: