Add support for password protected Maven repositories in ibiblio resolver

There doesn't appear to be a way to access repositories that are protected by username/password.

In the case I encountered, the repository had public access, but when it is provided with an authenticated user, then an extended set of artifacts is made available. Not being able to specify the username/password via the ivy-settings meant I was only able to access the public artefacts.

The suggestion is to use a similar approach to the 'ssh' resolver and add support for username/password elements.