TODO
* release as rip
* write man page webfinger.1
* add CONTRIBUTING
* play nice with gem man
* semver
* document everything as tested
* nodoc everything without docs
* see if redfinger's docs map at all
* prettify the script output
* ensure security
* check hm:Host
* check final /XRD/Subject
* test 3** redirects
* REXML support
* collect common rel values into a enum module
* put license info in every file
* find out if ruby has a default debug flag
* find well known uris via WellKnown.find(uri, :host_meta)
Reference Specs
* host meta http://tools.ietf.org/html/draft-hammer-hostmeta-13
* webfinger
* xrd http://docs.oasis-open.org/xri/xrd/v1.0/xrd-1.0.html
* lrdd http://tools.ietf.org/html/draft-hammer-discovery-06
* link header http://tools.ietf.org/html/rfc5988
* versioning-rels http://tools.ietf.org/html/rfc5829
other clients
* webfingerclient-dclinton.appspot.com/
* webfinger.org/lookup/darron@froese.org
* web.mailana.com/labs/findbyemail/