misc/vim: add a gofmt_command flag for :Fmt
misc/vim: add a gofmt_command flag for :Fmt

R=dsymonds, dominik.honnef, n13m3y3r, rsc, kamil.kisiel
CC=golang-dev
https://codereview.appspot.com/22940044

Committer: David Symonds <7f6bb564ed9e580d4f0aa90d53b34578e5d24cb9@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang