Ask before turning on Bluetooth to add a contact.

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -120,6 +120,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		}
 	}
 
+	@Override
+	void setEnabledByUs() {
+		wasEnabledByUs = true;
+	}
+
 	@Override
 	@Nullable
 	String getBluetoothAddress() {