Add badges/CI: Travis CI, automatic push of gh-pages, Greenkeeper, coverage

I heard badges improve a project’s perceived quality by users 😄 I’d suggest the following ones:

• Travis CI (+ badge)
• Automatic push of demo, and
• Automatic push of API documentation to gh-pages via Travis CI (@makimenko how did you generate the files in gh-pages? What was the command you ran?)
• Greenkeeper (+ badge)
  (I just npm installed this repo to test it and NPM warned me about “20 vulnerabilities”! Greenkeeper would have prevented that.)
• Maybe coverage (+ badge), but we only have few tests, though. But that could kickoff providing more tests!

See https://github.com/ComFreek/async-playground (shameless self-promotion) or any other repository. Popular repositories tend to have them most.

What do you think? I could do a PR in the next days.

[makimenko]

Nice

• steps 1-5 completed (thanks for a very good option for open-source CI)
• step 6 in progress (waiting for PR from Greenkeeper)

[ComFreek]

Yay, the latest commit fixed it, see https://makimenko.github.io/angular-template-for-threejs/.

@makimenko What do you think about making a link to the API documentation from within the README? I know there’s already the link to gh-pages from the repo description, but I think having an extra link with text “API docs” or something like that would be beneficial. Have to go now, otherwise, I’d have it done myself.