UTF-8 support fix for RDFa files

RDFa files list passed directly to RDFAParser change from using
ET.fromString() which expects ascii, to an ET.parse which is passed an
UTF8 parser

read_schemas adjusted to send file list instead of list of strings to
parser.
Merge pull request #111 from Dataliberate/master

UTF-8 support fix for RDFa files