Changed the way users can pick simulators

In lock step with https://github.com/robovm/robovm/pull/510 i changed the way users can specify the device type when launching a simulator. The shortcuts for launching an iPhone or iPad simulator are still in tact and will select the first device with the highest SDK version.

The launch configuration allows the user to select a specific device type id (device type + sdk version) from a drop down box, replacing the old behaviour of selecting a family and SDK.

![New Launch Dialog](http://libgdx.badlogicgames.com/uploads/Screen%20Shot%202014-09-23%20at%2021.39.13-tzbiUPn5HN.png)

On a related note: users can not select which SDK they want to build against (unless specified in robovm.xml). The SDK setting in the old dialog only seems to have been passed to ios-sim, but not to the compilation stage. We should probably extend the RoboVM project settings dialog to let users specify which SDK they want to build against. That dialog currently only sports settings for incremental compilation.