Add map tiles related ini settings and replicate bash script logic.
Optimize the export_to_csv part of the map creation job.

Using offset/limit keeps the peak memory usage in check (~250mb).
Doing the division on the Python side avoids SQLAlchemy helpfully
creating Decimal objects for the return values. And moving the
writelines call out of the loop avoids many I/O calls by writing
1 million lines at once, with currently ~47 million in the end output.
Restrict tile generation and map view to web mercator bounds.

On the map view we allow some overscrolling, before bouncing the view
port back into the bounds.
Dynamically look up datamap tiles layer from config setting.

Also allow the configured domain as part of the CSP image sources.
Respect the configured protocol for the assets domain.
Expose concurrency for map tiles rendering as a command line option.
Include filechunkio for boto's s3_put tool.
Add 'count' column to blacklists, rename 'created' to 'time', cc #238
Merge code paths for ichnaea.tasks.mark_moving_{cells,wifis}, cc #238