Wildcard global scopes

[cavis]

Hit an issue in ID, when requesting a wildcard token for just feeder:* scopes.

The ResourceMap & operator was dropping some scopes:

m1 = PrxAuth::ResourceMap.new("*" => "read-private feeder:read-private")
m2 = PrxAuth::ResourceMap.new("*" => "feeder:read-private")

# before, it was dropping the global read-private entirely!
(m1 & m2).as_json
{}

# after this PR, it correctly intersects them
(m1 & m2).as_json
{"*" => "feeder:read-private"}