largefiles: use revisions as a ui.progress unit
Using plural form is consistent with other progress units, and "1 out of 5
revisions" sounds more correct. Also, tests don't show this, but if you have
'speed' item in progress.format config, it shows e.g. '100 revisions/sec',
which also seems better.
# The 9mail to support patchbomb and other email wrappers
[email]
method = /bin/mercurial/9mail