Add Rake better automate testing locally & via Travis CI

Paves the way for additional testing automation as well
Add unit testing via ChefSpec

Berkshelf is also added to make ChefSpec tests easy to run
Add integration testing via Test Kitchen & Serverspec

Integration testing for:

* Ubuntu 12.04
* Ubuntu 14.04
* CentOS 5.10
* CentOS 6.5
Merge pull request #8 from evertrue/add-test-goodies

Add unit & integration testing, tied in to Travis