fix None bug for simple schemas like ogp
address nonstandard namespace bug (ie rnews)
add the _expand_qname function to validator
takes a qname (rnews:creator) and returns the name with namespace prefix expanded to uri (http://dev.iptc.org...etc...#creator)
also, move _validate_class overrides to use ValidationWarning
remove some dead weight
change error level from ERROR to WARNING for duplicatoin
only expand qnames that are potentially valid (on the basis of type)

remove todo
a journal entry about this morning's bugs
add a validator for the rdfa implementation of schema.org
this implementation is used on semanticweb.com alongside rnews, which causes some problems
cache schemas locally
this reduces the number of web requests performed over a given set of validations