Optimized boot time loading perf

I moved the bus and stop info loading from boot time to the PC_SelectionChanged event if the first pivot selected is Favorites or Recent. The last known location is set at boot time directly to be able to access Favorites and Recent data right away instead of having to wait for the location and routes data to load.
If you're not going to cast this explicitly, then you need to do an iv (viewModel != null) check below. Otherwise, just cast it explicitly.