Refactor API between app and bluetooth

companion/app.py

 from kivy.app import App
 
+from .bluetooth import MynitBluetooth
 
 class MynitCompanionApp(App):
-    pass
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self._bluetooth = MynitBluetooth(self)

companion/bluetooth.py

@@ -4,22 +4,14 @@ from able import BluetoothDispatcher
 
 class MynitBluetooth(BluetoothDispatcher):
 
-    def __init__(self):
-        super().__init__()
+    def __init__(self, app, *args, **kwargs):
+        super().__init__(*args, **kwargs)
 
-        self.available_devices = []
+        self._app = app
+        self._available_devices = set()
 
-
-    def scan(self, seconds):
         self.start_scan()
-        sleep(seconds)
-        self.stop_scan()
 
 
     def on_device(self, device, rssi, advertisement):
-        if not device in self.available_devices:
-            self.available_devices.append(device)
-
-
-    def connect(self, device):
-        self.connect_by_device_address(device.getAddress())
+        self._available_devices.add(device)