Build: Update Node support versions

Includes our supported versions in package.json to clarify the
current support.

This also brings our support policy in line with Rollup, so we can
avoid having to switch versions for building.

Fixes qunitjs#1067

.travis.yml

@@ -1,10 +1,10 @@
 sudo: false
 language: node_js
 node_js:
-  - "0.10"
   - "0.12"
   - "4"
   - "6"
+  - "7"
 env:
   - NPM_SCRIPT=ci
 matrix:
@@ -22,11 +22,7 @@ matrix:
 before_install:
   - true && `base64 --decode <<< ZXhwb3J0IEJST1dTRVJTVEFDS19VU0VSTkFNRT1icm93c2Vyc3RhY2txdW5pMQo=`
   - true && `base64 --decode <<< ZXhwb3J0IEJST1dTRVJTVEFDS19LRVk9SllzeHJrVWk5aGJGVndkdW44ZUsK=`
-  # Use a recent version of Node to build
-  - nvm install 6
 script:
-  # Switch back to the version of Node we want to test against
-  - nvm use $TRAVIS_NODE_VERSION
   - npm run-script $NPM_SCRIPT
 cache:
   directories:

package.json

@@ -71,5 +71,8 @@
       "Tests"
     ]
   },
-  "main": "qunit/qunit.js"
+  "main": "qunit/qunit.js",
+  "engines": {
+    "node" : "0.12.* || 4.* || 6.* || 7.*"
+  }
 }