stats.inc.php: Improve definition of "added"

stats.inc.php: Improve definition of "added"

Until now, a package is listed under "Packages added in the past 7 days"
if it was added at most one week ago and if the last modification time
matches the submission time stamp. A package is considered "updated" if
it was modified at most one week ago and the modification time stamp
differs from the submission time stamp.

Since we are using Git to store packages now, there always is a delay
between package creation (which is handled in git-serve) and last
modification (which is handled by git-update). Thus, by the above
definitions, almost every package is considered "updated".

Since there is no reason for excluding packages that were both added and
updated within the past seven days from the "Packages added in the past
7 days" counter, we can drop the check whether the last modification
time matches the submission time stamp. Also, to identify packages that
were actually updated, we now only count packages that were modified at
least one hour after the initial submission.

Signed-off-by: Lukas Fleischer <lfleischer@archlinux.org>