Fix issue in list servers and list servers details

List servers and list server details has the `current_timestamp` defaulted to `None`, where as `set_resource_status` required it to compute the status, in case a server was created with `metadata` . 
When adding new optional arguments, they should always go at the *end* of a function signature.  For example, someone passing `name` by position will now be passing `current_timestamp` by position instead.  Auditing all the tests to be sure nobody was passing the values this way is a lot harder than simply leaving `current_timestamp` at the end and not having to go check.  If the goal here is to make it mandatory, simply raise an exception if `current_timestamp is None`.