Update vancouver.csl

Changes: 
+ display "inventor" after inventor's name
+ correctly display webpages (according to 2011 update)
+ display PMCID, or PMID (if available)
Hmm - but recommended for what? Citing Medicine is used as the basis for many journals (we still have it as the parent style for a pretty significant number) and I very rarely see PMCID/PMID required or suggested there. And, as I said, it's not in most of their examples. Moreover, we already have a style that is Vancouver with PMCID/PMID (the NLM grant style) so people who do require/want them have a way to get that.