Update and rename draft-uma-trust.xml to draft-uma-binding-obligations.xhtml

Updated content to reflect starting point of the current IETF draft (v.2) and current common name "Binding Obligations" in sync with the "keep alive" updated RFC submission at: http://tools.ietf.org/html/draft-maler-oauth-umatrust-01   GitHub (appropriately) automatically forked version to my Repo because I have no write access in the originating Repo at this time.