Currently, DavException objects can contain a whole HTTP response object, is problematic:

• a HttpResponse body may or may not be consumable (think about a streaming transfer that is already finished),
• it's not clear why the whole response is needed in the exception,
• it could cause problems when we try to serialize the exception,
• it couples a HTTP-level data class with a specific HTTP implementation.

So we should probably only take what we need (code, message, DAV:error XML element names, …) when the DavException is constructed.