Lower-/mixed-case keywords causing failure

[RoUS]

It appears that zonefiles that use lowercase class and RR type keywords are causing DNS::Zone.load to choke and throw an exception:

#! /usr/bin/ruby
require('rubygems')
require('dns/zone')

zdata = <<EOT
$ttl 3600
$origin dnszone.example.com.
@               in soa      ns1.example.com. hostmaster.dnszone.example.com. (
                            2012052400  ; serial
                            345600      ; refresh
                            3600        ; retry
                            604800      ; expire
                            3600        ; ttl
)
EOT

DNS::Zone.load(zdata)
=> RuntimeError: Unknown or unsupported RR Type
	from /usr/local/share/gems/gems/dns-zone-0.3.1/lib/dns/zone/rr.rb:56:in `load'
	from /usr/local/share/gems/gems/dns-zone-0.3.1/lib/dns/zone.rb:105:in `block in load'
	from /usr/local/share/gems/gems/dns-zone-0.3.1/lib/dns/zone.rb:91:in `each'
	from /usr/local/share/gems/gems/dns-zone-0.3.1/lib/dns/zone.rb:91:in `load'

There is no requirement that the keywords be uppercase.

I'll see if I can work up a patch for this.