No need for reference here.
Only attempt to set the logger if we have a factory.
Need to check both the standard and the non-standard headers here.

Some clients send 'Authorization' here. Allow for both.
Pass the request object instead of using $_SERVER.

Allows for mocking these values in tests.
Trim any stray ws from the parsed XML.
If the client was broken and didn't send the XML, we need to assume these values.
visibility
Add test for Autodiscover command parsing.
CHANGES