added ability to read buffered values from the raspberry

APED/app/src/main/java/com/example/aped/communication/Communicator.java

@@ -77,6 +77,27 @@ public class Communicator {
         requestQueue.add(request);
     }
 
+    /**
+     * Method to read a device value buffer from the raspberry.
+     * @param deviceName the name of the device
+     * @param responseListener the {@link Response.Listener} for defining
+     *                         actions to be performed on response
+     */
+    public void readBuffer(final String deviceName,
+                       final Response.Listener<JSONObject> responseListener) {
+        String url = "http://" + address
+                + ":" + port
+                + "/device/" + deviceName + "/buffer/";
+        JsonObjectRequest request = new JsonObjectRequest(
+                Request.Method.GET,
+                url,
+                null,
+                responseListener,
+                error -> handleError(error, "READ")
+        );
+        requestQueue.add(request);
+    }
+
     /**
      * Writes an api call to the endpoint of a device.
      * @param deviceName the name of the device