Adding Travis CI to test Rubies >=1.9.3

The PR was sent with the following:

1. I added Travis CI to the project and added Rspec as a testing tool.
2. All of the examples were tested with the mentioned gem and I've covered all of the scenarios previously tested with minitest.
3. I updated some of the file routes to work properly and updated the readme files as well.

[Here](https://travis-ci.org/jcabasc/refactoring-workshop/builds) you can follow the link to the Travis CI repo.

Let me know if has met your expectations.
Prefer single-quoted strings when you don't need string interpolation or special symbols.