Update vancouver.csl

Changes: 
+ display "inventor" after inventor's name
+ correctly display webpages (according to 2011 update)
+ display PMCID, or PMID (if available)
@fbennett, what would be the advantage of that over just adding additional, more specific terms and author-roles?

I'm opposed here since there isn't a logical connection between "original-author" and an inventor role.