Bug 888595 - Convert BluetoothManager bindings to WebIDL. r=bz, r=echou

This patch converts the BluetoothManager to WebIDL and removes the
old XPIDL bindings. The only user of BluetoothManager is the class
Navigator, which has been adapted to the change.
Bug 888595 - Convert BluetoothAdapter to WebIDL. r=bz, r=echou

In addition to converting BluetoothAdapter, this patch also converts
MediaMetaData and MediaPlayStatus to WebIDL. The old XPIDL-based
bindings have been removed.
Bug 888595 - Convert BluetoothDevice to WebIDL. r=bz, r=echou

We keep the old XPIDL files in place to stay compatible with existing
code. They can probably be removed when all bindings have been converted
to WebIDL.
Bug 888595 - Fix Bluetooth permission test. r=dchan