Fix Issue#3 - Tile Images generated by "Pin" and "Refresh" are different. Resolution is to call grid.UpdateLayout()

Fix: App crashes if choosing bus with empty stations_back, such as「公路客運」
Beautify LiveBusTile image with UpdateLayout
Add BackgroundExecution in LiveBusTile/WmAppManifest.xml
Add BusInfoVM to achive MVVM updated to UI View