Add options for DigitalGlobe Standard and Premium

[cshaa]

Source of the configuration is the last post of this thread.

[Vort]

@jonasstein:
It is ok to merge this change, I think.
But maybe it will be good also to remove MapQuest from config file?
And what about changelog? Should it contain such changes?

[jonasstein]

Are we allowed to distribute an access_token? I think not.

[Vort]

JOSM and iD distributes it:
https://josm.openstreetmap.de/wiki/Maps
https://raw.githubusercontent.com/openstreetmap/iD/master/data/imagery.json

Scanaerial is not worse.

[jonasstein]

We should clarify, if we may distribute it. If we may not, it can fire back. It really looks like an limited service which should not be used by external programs without payment. But perhaps I am wrong.

[Vort]

DigitalGlobe, Inc. is pleased to provide its high resolution satellite imagery to OpenStreetMap in support of its mapping initiatives. By using our imagery in the OSM editor, you understand and agree that you may only use our imagery to trace, and validate edits that must be contributed back to OSM...
Tracing? Yes. For OSM? Yes.

[katpatuka]

BTW: ESRI World Imagery works for me using the below settings:

server_api = tms
server_name = ESRI
server_url = https://{switch:services,server}.arcgisonline.com/arcgis/rest/services/World_Imagery/MapServer/tile/{zoom}/{y}/{x}
empty_tile_bytes = 1882
empty_tile_checksum = -1893505042