Update Lookupd address routine to support full URI

Updated Lookupd address to support full HTTP/HTTPS URI format

This should address #44

Go implementation: https://github.com/bitly/go-nsq/blob/master/consumer.go#L381-L405

Since this portion of `isAddr` is being re-used below in `isNSQLTCPAddresses` it seems like it should be DRYed up. the `isAddr` variants shouldn't be inner functions anymore.