Update .travis.yml for Node 8 support (#825)
Update .travis.yml for Node 8 support (#825)

* Update .travis.yml for Node 8 support

* Removed support for odd versions of Node

stems/google-api-nodejs-client,sqrrrl/google-api-nodejs-client,sqrrrl/google-api-nodejs-client,sqrrrl/google-api-nodejs-client,sqrrrl/google-api-nodejs-client,googleapis/google-api-nodejs-client,stems/google-api-nodejs-client,googleapis/google-api-nodejs-client,sqrrrl/google-api-nodejs-client,stems/google-api-nodejs-client,googleapis/google-api-nodejs-client,stems/google-api-nodejs-client,stems/google-api-nodejs-client