stash list: drop the default limit of 10 stashes

stash list: drop the default limit of 10 stashes

'git stash list' had an undocumented limit of 10 stashes, unless other
git-log arguments were specified.  This surprised at least one user,
but possibly served to cut the output below a screenful without using
a pager.

Since the last commit, 'git stash list' will fire up a pager according
to the same rules as the 'git log' it calls, so we can drop the limit.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>