Make Travis install mencoder.

Attempts to fix matplotlib#2678.

Author: dopplershift

.travis.yml

@@ -24,7 +24,7 @@ matrix:
 
 install:
   - pip install -q --use-mirrors nose python-dateutil $NUMPY pep8 pyparsing pillow sphinx
-  - sudo apt-get update && sudo apt-get -qq install inkscape libav-tools gdb
+  - sudo apt-get update && sudo apt-get -qq install inkscape libav-tools gdb mencoder
   # We use --no-install-recommends to avoid pulling in additional large latex docs that we don't need
 
   # We manually install humor sans using the package from Ubuntu 14.10. Unfortunatly humor sans is not