STH-Comet unable to handle uppercase characters in fiware-service header

[tazchalmers]

This took me a really long time to debug, but I have figured out that if an uppercase character is used in the fiware-service header, then STH-Comet returns no values.

With an all lowercase fiware-service header STH-comet returns values as expected.

Sorry, I don't have time to test if the same is true with the fiware-servicepath.

[jason-fox]

I'm guessing that this is somewhat related to telefonicaid/iotagent-node-lib#1024 - I'll add in a note to the text to make this more visible.