Travis CI added to Continuous Testing recipe

[AJ-Acevedo]

All set!

question  Continuous testing?
          1)  None
          2)  Guard
          3)  Travis CI
          4)  Guard with Travis CI
       setup  Enter your selection: 

I tested both options and it works as expected.
Let me know if you'd like me to make any changes.

I added some Travis documentation links in the .travis.yml file, but if you don't think they belong there I can pull them out. Figured they'd be helpful.

[vfonic]

I'd separate this in a new recipe recipe/continuous_integration.rb. On this way, one can add other CI platforms, like CircleCI (that's the one we use at DVELP).

Also, I don't think guard and travis have much in common / serve the same purpose. Just that string "Guard and Travis CI" looks really confusing if you don't read the recipe code. I wouldn't know what it means, does it setup guard to run with travis CI? WAT!

https://www.youtube.com/watch?v=FqhZZNUyVFM