Merge pull request #36 from danbri/master

Changes for schema.org 1.6
Merge pull request #37 from danbri/master

Adding examples for license property.
code clean up in license examples
rel attribute is typically in the a element, not in the image

see http://wiki.creativecommons.org/RDFa
Merge pull request #39 from danbri/master

More changes for 1.6, removed mentions of non-property 'asset', added Microdata/RDFa for Role examples.
Merge pull request #38 from scor/license-example-tweaks

License example tweaks
Keeping scor's changes except that in RDFa, rel="license" works better
(and matches the original page's approach more faithfully).