Basic iOS7 Rotation support

This pull request adds basic iOS7 rotation support on the 0.9.x line of development:

* Rotation enabled, not throwing NotImplemented no longer
* Convert touch coordinates based on rotation mode before touching => touching the correct element when rotated.

Fixes #207.
There might be some rough edges, but it passes a [simple test suite](https://github.com/driis/calabash-ios-example/blob/ios7test/features/rotation.feature) I built based on the example app. It is also tested on a real-world project that I cannot disclose, with a few of our UI tests that have been converted to iOS7.

#### Known issue
It seems that for apps that startup in landscape mode (locked orientation), `device_orientation` does not always detect the correct orientation. I solved it for our test suite by calling `rotate` explicitly a few times on launch so to align Calabash' view of the simulator with the actual world. Have not looked into the underlying issue for this.