WIP: DNS case-insensitivity

As defined by [RFC1035](http://www.ietf.org/rfc/rfc1035.txt) 2.3.3, DNS should done in a case-insensitive manner. This pull will lowercase node data in the state store and always compare incoming DNS queries in lowercase.

Resolves #189.
I think we can remove this now with the indexes. This way, at least we preserve casing in the log messages for the query