Add support for OSM-blacklisted URL Patterns

[slibby]

Currently, http://api.openstreetmap.org/api/0.6/capabilities provides a list of regex-able URL patterns to block, so that a user does not use Google imagery to digitize, for example.

While there are no vector sources in that list currently, it would be a good show of faith to the larger community and a good preparatory feature to have the GeoServices branch respect this list that as well, checking any user-provided URL against that blacklist.

see openstreetmap#4164 (comment)

[mapmeld]

I can link this with iD's current system for checking the blacklist, context.connection().imageryBlacklists()