Improve version of Node.js used for testing travis-CI

[abetomo]

• Add the LTS version and the latest version of Node.js to .travis.yml
• Remove Node.js 0.10 from .travis.yml
  • The reason is that 0.10 is End-of-Life.

Reference: https://github.com/nodejs/Release

[abetomo]

Closed because it has been merged.