Request version bump of NodeJS in Travis

[skoblenick]

You probably have noticed this yourself; it isn't documented anywhere, but creating a package from master requires Node 6.9.2 yet your travis build defines NodeJS 4.5.

Attempting to run npm run package within Travis CI results in the following failure.

The command "./node_modules/.bin/rollup -c --environment ROUTER" exited with 1.
0.20s$ rollup -c --environment ROUTER,MINIFY
'default' is imported from external module 'rollup-plugin-visualizer' but never used
Unexpected token {
SyntaxError: Unexpected token {
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:373:25)
    at Module._extensions..js (module.js:416:10)
    at Object.require.extensions..js (/home/travis/build/username/ui-router/node_modules/rollup/bin/rollup:764:6)
    at Module.load (module.js:343:32)
    at Function.Module._load (module.js:300:12)
    at Module.require (module.js:353:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (/home/travis/build/username/ui-router/rollup.config.js:6:46)
    at Module._compile (module.js:409:26)
Type rollup --help for help, or visit https://github.com/rollup/rollup/wiki
The command "rollup -c --environment ROUTER,MINIFY" exited with 1.

The issue is related to the rollup-plugin-visualizer. The plugin is written in ES6 and uses unsupported features in 4.5 such as object deconstruction; specifically Line 17 of plugin.js. Version bumping NodeJS in your .travis.yml will resolve the ability to run npm run package within your build.

Doing so with a few additions to your .travis.yml and Travis build you could auto-release based on version tags; see my fork. If you're interested I'll put in a PR.