Travis-CI testing

This pull request adds Travis-CI continuous integration. 
Here is the current build status: [![Build Status](https://travis-ci.org/bollwyvl/jquery-handsontable.png?branch=travis-testing)](https://travis-ci.org/bollwyvl/jquery-handsontable)

Ouch. 10/137 is not so good. The bright side is that it seems to be a few key issues, such as `priv.settings.data` being undefined occasionally, and that the behavior of the generated `_SpecRunner.html` is the same as it was before in Chrome, though FF may have picked up a bit of a flutter.

I hope this helps in getting to at least a baseline for doing automated testing, but due to the selection of browsers supported, this won't cover everything. But who knows? Maybe a headless IE7 can be run under Wine or something.