Parses a list of MIME types, as they occur in the Accept header; for
example:
text/xml, text/plain; q=0.8, text/html; q=0.7, text/ *; q=0.3, * /*;
q=0.1
ABCDEFGHIJKLMNOPQRSTUVWX
Copyright (c) 2011, iPlant Collaborative, University of Arizona, Cold Spring Harbor Laboratories, University of Texas at Austin.