Updates to itinerary page:
1.) Allow selecting/unselecting by tapping anywhere on item row
2.) Display priority text with color corresponding to priority
3.) Add select all/clear all buttons
4.) Created ItineraryViewModel to house collection of all service items, included service items, and commands
5.) Added other utility classes
6.) Other minor UI tweaks
Merge branch 'master' of https://github.com/chrisahill/Field-Worker-Assistant