Proof of concept: Alloy support

We ran into some trouble running `tio2` on our Alloy app. After a while we realised that it was Alloy overwriting the generated app.js from `tio2` in the temp. build folder. So we wanted to add Alloy support to `tio2`. We are not yet fully satisfied, but wanted to run the setup with you as a proof of concept. It is working at the moment.

What we did:
* Check as early as possible if app is Alloy app, but checking the existence of the `ti.alloy` plugin in the original tiapp.xml
* If app is Alloy app, run Alloy compile process
* Run the rest of the `tio2` build process

The problem we ran into is that we needed to execute the `alloy compile` async. It might be nicer to put everything in `async.waterfall` and execute that after Alloy is completed, or directly when app is not an Alloy app.

We added an `exampleAlloy` folder to test the Alloy support.