update travis config

Author: krvajal

.travis.yml

@@ -1,9 +1,7 @@
+language: generic
+
 sudo: false
-language: node_js
-node_js:
-  - "iojs"
-  - "7"
-  
+
 os:
   - osx
   - linux
@@ -16,8 +14,20 @@ before_install:
     fi
 
 install:
+  - TRAVIS_NODE_VERSION="6";
+      # Clear out whatever version of NVM Travis has as it is old.
+  - rm -rf ~/.nvm;
+      # Grab NVM.
+  - git clone https://github.com/creationix/nvm.git ~/.nvm;
+      # Checkout the latest stable tag.
+      # Note that you can just hardcode a preferred version here.
+  - (cd ~/.nvm && git checkout `git describe --abbrev=0 --tags`);
+      # Install the desired version of Node
+  -  source ~/.nvm/nvm.sh;
+  -  nvm install $TRAVIS_NODE_VERSION;
   - npm install
   - npm run vscode:prepublish
 
 script:
+  - npm run lint
   - npm test --silent