adds rest communication

- test cases for push and pop
- rest singleton instantiated in MainApplication
  access through context
- pop and peek work, push needs encryption process
  still

app/src/main/res/layout/fragment_camera.xml

@@ -6,9 +6,9 @@
     android:layout_height="match_parent"
     tools:context=".SecondFragment">
 
-    <androidx.camera.view.PreviewView
+    <!--androidx.camera.view.PreviewView
         android:id="@+id/viewFinder"
         android:layout_width="match_parent"
-        android:layout_height="match_parent" />
+        android:layout_height="match_parent" /-->
 
 </androidx.constraintlayout.widget.ConstraintLayout>