Improve git pull --quiet behaviour

While trying to cleanup some cron jobs that do "git pull", I found out
that "-q" doesn't behave as expected. The following two small patches
improve the handling of this option.

My tests show that now 'git pull -q' when there are no changes is silent
as expected and plain 'git pull' has the previous behaviour. I hope that
I followed the code style correctly while modifying the files.

Overall diff stats:
 Documentation/git-merge.txt     |    2 +-
 Documentation/merge-options.txt |    4 ++++
 git-merge.sh                    |   19 +++++++++++++------
 git-pull.sh                     |    8 +++++---
 4 files changed, 23 insertions(+), 10 deletions(-)

regards,
iustin