18. Refractor to include navigation between pages.
	- Add IMessageBus and MessageBus Class
	- Create a new view Home.xaml, and HomeViewModel. Move all the view from MainWindow.xaml to Home.xaml. Move all the code from MainWindowViewModel to HomeViewModel.
	- In MainWindow.xaml Just keep a menu strip at top and a Frame Name=MainFrame below it.
	- Create the property for HomeViewModel in ViewModelLocator. Bind Home.xaml to its ViewModel.
	- In App.xaml.cs add a static IMessageBus. On startup of application instantiate this messagebus.
	- In the MainWindowViewmodel use this App.messagebus to perform Navigation activity on the MainFrame.
Fix regex of Numeric validator.