Type of proxy credentials should be decided by apns user #287
Description
The framework supports credentials in the type of Basic/Digest or NTLM to connect to a proxy with.
The type of credentials used by the proxy is today found out by first trying to connect without credentials and then finding out the type by looking in the response from the proxy server.
The user of this API is probably aware of which credentials server is used and can therefore set the type of credentials in the "withProxy" call.