Convert to non-sudo builds for travis

.travis.yml

 # Travis CI configuration file for running tests
 language: python
+
 branches:
   only:
     - master
+
 python:
   - "2.7"
-sudo: required
+
 services:
   - docker
+  
+addons:
+  apt:
+    packages:
+      - nodejs
+      - python-demjson
+
 install:
-  - "sudo apt-get update -qq"
-  - "sudo apt-get install -y nodejs python-demjson"
   - "pip install --allow-all-external -r requirements.txt"
   - "pip install --allow-all-external demjson"
+
 env:
   - MAKE_TARGET=docker.test
   - MAKE_TARGET=test.syntax
   - MAKE_TARGET=test.edx_east_roles
+
 script:
   - docker --version
   - make --version