use python2 for tests with old node

Author: jellelicht

.travis.yml

@@ -57,7 +57,7 @@ matrix:
       addons:
         apt:
           sources: [ 'ubuntu-toolchain-r-test' ]
-          packages: ['xvfb','libasound2','libx11-6','libglib2.0-0','libgtk2.0-0','libatk1.0-0','libgdk-pixbuf2.0-0','libcairo2','libfreetype6','libfontconfig1','libxcomposite1','libasound2','libxdamage1','libxext6','libxfixes3','libnss3','libnspr4','libgconf-2-4','libexpat1','libdbus-1-3','libudev1']
+          packages: ['xvfb','libasound2','libx11-6','libglib2.0-0','libgtk2.0-0','libatk1.0-0','libgdk-pixbuf2.0-0','libcairo2','libfreetype6','libfontconfig1','libxcomposite1','libasound2','libxdamage1','libxext6','libxfixes3','libnss3','libnspr4','libgconf-2-4','libexpat1','libdbus-1-3','libudev1', 'python2.7']
       script:
         # test node-webkit usage
         - ./scripts/test-node-webkit.sh