Update dashboard icons when resuming activity.

Fixes #186. 

The issue is that DashboardActivity doesn't receive events while it's paused. This appears to be device-dependent because it depends on the relative speed of resuming the activity vs delivering the event. If the activity resumes quickly enough, it will register its event listener and catch the event. If not, it won't update its icons until it's recreated, e.g. by rotating the screen.

See merge request !31