Bootstrap logic currently uses a boxed version of the geofence #54

Describe the bug
The current logic for bootstrap uses a boxed version of the geofence, this results in areas being scanned that don't need to be if the provided geofence already excludes areas that don't have stops/gyms ie farm land or forest areas on the edges of towns.

To Reproduce
Steps to reproduce the behavior:
Create a geofence that is not a square and avoids an area that would not have stops/gyms.
Create a bootstrap instance using the geofence.
assign device to the instance
watch device location on the map or watch spawn point that are discovered, you will see the device is bootstrapping areas outside of the geofence.

Expected behavior
bootstrap areas only in the geofence.