FishEye implementation of SAL UserProfile.getProfilePIctureUri does not return URI relative to base URI

The SAL API documentation states that UserProfile.getProfilePictureUri()

The URI will either be relative to the application's base URI, or absolute if the profile picture is being served by an external server

Currently, when the avatar URI is using the internal avatar service, the implementation returns a URI that includes the context path (which is also included in the base URI). This is incorrect according to the documentation and also makes it difficult for plugins to construct an absolute URI for the avatar picture.