Added Travis CI integration

As [Travis CI](https://travis-ci.org) now supports objective-c and [xctool](https://github.com/facebook/xctool), which allows to run tests from CLI with ease, is released. It's super easy to have continuous integration for open source projects! :)

I'm happy to propose to add support for Travis CI for Kiwi! :) With these changes each time when somebody pushes something all tests will be run on Travis CI. In case of failure notifications will be sent.

Example of test results can be found [here](https://travis-ci.org/yas375/Kiwi).

Also it is needed to enable Travis CI hook for the repository on Github. The easiest way to do this is to login into [Travis CI](https://travis-ci.org) with Github account. On [profile page](https://travis-ci.org/profile) enable sync for `allending/Kiwi` repository. And that's all! :)