Try a reinstall of matplotlib with pyqt support

.travis.yml

@@ -100,6 +100,14 @@ script:
       fi
     - travis_retry pip install --no-deps astropy
 
+    # Reinstall matplotlib with pyqt support
+    - pip uninstall matplotlib
+       - if [[ $ENV != python=2.6* ]]; then
+            travis_retry pip install matplotlib --no-index --find-links=http://wheels.scikit-image.org/;
+      else
+         pip install matplotlib==1.1.0;
+      fi
+
     # Matplotlib settings - must be updated after PyQt is installed
     - export MPL_DIR=$HOME/.config/matplotlib
     - mkdir -p $MPL_DIR