org-open-file: ignores browse-url settings

[raman@google.com]

Function org-open-file uses customization variable org-file-apps to
decide how to open a file.
Unfortunately it's also making it difficult / impossible to set it up
so that  org files exported to HTML open in Emacs using EWW ---
-specifically: the customization interface for org-file-apps claims to
let you provide a custom lisp form which in principle should let one
specify browse-url -- (admittedly convoluted ) but even that fails to
work -- mostly because the documentation is somewhat light with
respect to showing how one gets ones hands on the matched link.
-- 

--