commit notify: default to reverse order in regproj.cgi
Most people reading through the new revision list in a commit notify
email will probably want to see revisions in oldest to newest order to
make sense of any comments that talk about things committed in earlier
revisions.
To this end, make the "Show oldest first" checkbox default to checked on
the regproj.cgi page.
Also take this opportunity to expand the hover help a bit to make it
clear what email the checkbox affects.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>