Add view controller for tours map
Hook up self-guided tour map view
Add annotation class to wrap tour stops
Set up tour map annotation views with stock pins
Display MIT map tiled overlay
Display placeholder numbered annotations for each stop
Render polyline for tour route
Add WYPopoverController to external submodules
Add view controller for tours map callout content
Present popover in place of tours map callouts
Allow line wrap on callout labels
Display correct distance to stop from user location
Clean up custom callout and map behavior

Unfortunately the approach here is to concede on the ideal
"normal" map behavior, in which callouts smoothly scroll
with the annotation. This is a stop-gap alternative until
a better custom callout solution is implemented.
Scroll annotations away from map edge before showing callout