Adding an icon for submitted graffiti.
Fix the bug with the graffiti not being saved with the new GPS location.

Other changes:
* display an indeterminate progress dialog while looking for a better location.
Get rid of the IGraffitiRepository instance variable.
Don't publish a notification when a new location received.
Creating a GraffitiDetailViewModel and moving some logic into that.
Add some more sophisticated logic for handling when we should accept a new GPS location.
Add a cancel option to the GraffitiDetailActivity

Not sure I like the icon...