Merge pull request #14 from VsevolodGolovanov/issue_13_add_update_tray_icon

Closes #13

Add method to update tray icon

Author: infeo

src/main/java/org/cryptomator/integrations/tray/TrayMenuController.java

@@ -30,6 +30,14 @@ static Optional<TrayMenuController> get() {
 	 */
 	void showTrayIcon(byte[] imageData, Runnable defaultAction, String tooltip) throws TrayMenuException;
 
+	/**
+	 * Updates the icon on the system tray.
+	 *
+	 * @param imageData What image to show
+	 * @throws IllegalStateException thrown when called before an icon has been added
+	 */
+	void updateTrayIcon(byte[] imageData);
+
 	/**
 	 * Show the given options in the tray menu.
 	 * <p>