add check before Upload, for now disabled by default,
that files do not change when run through gofmt.
enable by adding

	[codereview]
	force_gofmt = True

to .hgrc or .hg/hgrc.

add doc strings for a few more commands.
rename codereview-login to code-login
to make module doc visible.

R=r
CC=gri
http://go/go-review/1018056