Pass concept URI, labels etc. as JavaScript variables

[osma]

The current HTML template has a block which passes a few bits of information to javascript code:

<!-- variables passed through to javascript -->
var lang = "en";
var content_lang = "en";
var vocab = "yso";

For the benefit of additional javascript code (e.g. widgets that perform lookups into bibliographic databases), we could also add:

• URI of current concept (so it doesn't have to be looked up from HTML code)
• prefLabel of current concept in all languages (ditto)
• uriSpace setting of current vocabulary