set window icon for the Browser dialog

I think we need to include the resources, and then set the main window icon:

icon = QtGui.QIcon()
icon.addPixmap(QtGui.QPixmap(":/images/mask-icon.png"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
MainWindow.setWindowIcon(icon)       

(from redmine: created on 2016-12-06)