REFACTORING: Abstract out memento related calls to MementoHandler, which implements timegate and timemap rendering.
DefaultMementoHandler provided which follows the protocol.
EmbeddedCDXServer provides experimental extensions
FIX: Fix bug in MementoLinkWriter timemap serializer
Add support for optional status field in MementoUtils
AccessPoint: don't redirect in case of old-style revisit, treat it as a proper revisit