The simulator requires old adb module if needed

The Simulator module now dynamically requires adb/adb (the new _adb.js_) or adb/adb-fallback (the _adb.js_ before my huge pull-request).
Now we can continue to break compatibility with adb's socket IPC interface without worrying about the case where _adb_ is already running on a user's computer.

All tests except for _test-receipts_ passes (_test-reciepts_ was already broken see #748) and everything seems to work when _adb_ is either running or not running before starting up the simulator 

Thanks @nickdesaulniers for noticing that the simulator wasn't detecting devices when _adb_ was running in the latest preview build.