Implement connectivity listener

app/src/main/AndroidManifest.xml

@@ -5,10 +5,11 @@
     <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
     <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
     <uses-permission android:name="android.permission.READ_PHONE_STATE" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
     <uses-permission android:name="android.permission.WAKE_LOCK" />
-    
+
     <application android:label="@string/app_name" android:icon="@drawable/ic_launcher" android:allowBackup="true" android:theme="@style/TraccarTheme">
         
         <activity android:name=".MainActivity">