Merge branch 'sb/push-options'

"git push" learned to accept and pass extra options to the
receiving end so that hooks can read and react to them.

* sb/push-options:
add a test for push options
push: accept push options
receive-pack: implement advertising and receiving push options
push options: {pre,post}-receive hook learns about push options

diff --cc Documentation/config.txt
Simple merge

diff --cc Documentation/git-push.txt
Simple merge

diff --cc transport.c
Simple merge