changes to travis.yml.

- Add gcc-4.9 to travis host.
- namespace travis variables as seem to conflict with docker env.
- set versions on travis.
- run npm tests again.
- slight readme mod for docker

.travis.yml

@@ -1,12 +1,19 @@
+dist: trusty
 sudo: required
 
 env:
-  DOCKER_COMPOSE_VERSION: 1.11.2
+  TRAVIS_DOCKER_COMPOSE_VERSION: 1.12.0
+  TRAVIS_GCC_VERSION: 4.9
+  TRAVIS_NODE_VERSION: 4.8.1
+  TRAVIS_NPM_VERSION: 4.4.4
 
 before_install:
+  - sudo apt-get update -y
+  - sudo apt-get install -y gcc-${TRAVIS_GCC_VERSION}
+  - npm install -g npm@${TRAVIS_NPM_VERSION}
   - sudo curl -fsSL https://get.docker.com/ | sh
   - if [ -e /usr/local/bin/docker-compose ]; then sudo rm /usr/local/bin/docker-compose; fi
-  - sudo curl -L https://github.com/docker/compose/releases/download/${DOCKER_COMPOSE_VERSION}/docker-compose-`uname -s`-`uname -m` > docker-compose
+  - sudo curl -L https://github.com/docker/compose/releases/download/${TRAVIS_DOCKER_COMPOSE_VERSION}/docker-compose-`uname -s`-`uname -m` > docker-compose
   - sudo chmod +x docker-compose
   - sudo mv docker-compose /usr/local/bin
   - sudo docker-compose build --no-cache --force-rm
@@ -15,13 +22,13 @@ before_install:
   # ^^ Note - need to come up with some way of checking the output from docker run
   # that it was a success... perhaps the nodejs server can output a success message?
 
-#language: node_js
-#
-#node_js:
-#  - "4.8.1"
-#
-#install:
-#  - "npm install"
-#
-#script:
-#  - "npm test"
+language: node_js
+
+node_js:
+  - "${TRAVIS_NODE_VERSION}"
+
+install:
+  - "npm install"
+
+script:
+  - "npm test"