bug#49 Fixed by ensuring that intents for different contacts/groups can be distinguished from each other when resolving PendingIntent refs

- replaced use of Object instance mutex with a private final Lock object
- replaced Object signaling with specific condition signalling

The project is now built as an Android project (via Eclipse or
ant). Tests have been moved to a separate project so they can exist
outside the Android build process. A basic Android app structure has
been created. A Bluetooth plugin for Android has been added, and the
Bluetooth plugin for J2SE has been modified to use the same techniques.