PROV-ISSUE-320 (dgarijo): Change the name of prov:Quotation

PROV-ISSUE-320 (dgarijo): Change the name of prov:Quotation

http://www.w3.org/2011/prov/track/issues/320

Raised by: Stephen Cresswell
On product: 

I wrongly thought prov:Quotation was a kind of
Entity rather than a kind of EntityInvolvement, and I correspondingly
misread hadQuoterAgent, hadQuotedAgent property as relating an Entity to
an Agent and thought that it ought to be a specialization of
wasAttributedTo.  The way it's actually modeled does match PROV-DM, so
there's nothing wrong here, but it might be worth considering renaming
prov:Quotation to help avoid the tempting misreading.