install synapse prerequisites as part of build

.travis.yml

@@ -15,5 +15,7 @@ addons:
     chrome: stable
 install:
     - npm install
+# install synapse prerequisites for end to end tests
+    - sudo apt-get install build-essential python2.7-dev libffi-dev python-pip python-setuptools sqlite3 libssl-dev python-virtualenv libjpeg-dev libxslt1-dev
 script:
     ./scripts/travis.sh