Support travis build

* Impl matrix test
  * (ruby 1.9.3, 2.0.0, 2.1.2)  x (Rails 3.2, 4.0, 4.1) = 9 patterns !
* Travis setting manual
  * http://sue445.hatenablog.com/entry/2013/06/01/170607
* example
  * https://travis-ci.org/sue445/komachi_heartbeat