Request#header(String) should be case insensitive for HTTP requests

[udoprog]

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html
From 4.2 Message Headers: "Field names are case-insensitive."

This will otherwise cause problems when interacting with proxies or clients that perform pre-emptive all-to-lowercase/uppercase example here before the request hits the Apollo-based service.

[pettermahlen]

What exactly is the problem in the Apollo code base?

[udoprog]

Request#header(String) is not case-insensitive, which should probably be handled by ApolloRequestHandler in the jetty-http-server module returning using a map that is all-lowercase, and providing a request object with alternative implementation that String#toLowerCase()'s the key before looking it up.

[pettermahlen]

Right, of course, it was in the title. We should define whether Request itself considers headers to be case-sensitive or not, I think. I don't have any strong opinions about that, but I think I would like to make it case-insensitive like for HTTP.

[pettermahlen]

Addressed in #93

[pettermahlen]

Fixed via #96