Support for stress maps

This release adds support for adding incidents (safe/suck). Finally!
Concretely, it:

• adds a new factory to deal with incidents
• allows users to add incidents by clicking on the trip details and selecting safe/suck
• retrieves and displays unpushed incidents from the cache
• retrieves pushed incidents as part of the trip geojson
• displays user reported incidents in the diary
• displays aggregate incidents in the heatmap, which now allows you to choose between counts and incidents