Update .htaccess to for dereferencing the vocabulary URI

based on the accept header and use see other location
see http://www.w3.org/TR/swbp-vocab-pub/

Forward base url to the DDI Alliance RDF page
Validation and rendering fixes for HTML5 and XHTML

removed extra <section/>
added missing tr tags
close <dd> tags
close <meta>, <img>, and <br> tags
renamed duplicate id literals-to-identifiers to
mapping-from-DDI-XML-to-DDI-RDF
escaped < and > in <pre> blocks
escape &&
in html5, <ul> and <h4> can not be nested in <p>. switch to <div>
added alt tags
Merge pull request #84 from DanSmith/master

Update htaccess for content negotiation and validation fixes for the document