Pass standard input through to all hooks

[getsnoopy]

Some git hooks can be passed additional information through standard input (e.g., the pre-push hook), so this commit handles that properly. Since stream data can be consumed only once but multiple hooks may need to use it, capture the stream data once and pipe it to each child process individually.

Fixes #26

[coveralls]

Coverage increased (+0.09%) to 95.238% when pulling 7df937f4fbec01c0f79f4be3c66b7d19ab08d075 on getsnoopy:master into 069d80a9399ebe531563e2234cc83d1abb1b8ef4 on tarmolov:master.

[getsnoopy]

I added an extra test in there that checks to see if everything works properly even if no input is passed in via STDIN.

[tarmolov]

Sorry for delay.

I was thinking about this pr. It makes the tool more complicated and even fragile because of async behavior. So, I decided to decline supporting such feature for a while.

Thank you for your help and your time. I very appreciate that and sorry for bad news : - /

[getsnoopy]

Hey @tarmolov, I'm wondering how you feel about this feature now. We really need this, since we need the hook scripts to be able to see where commits are being pushed in the pre-push hook for example. There's no alternative to it at the moment.

[getsnoopy]

@tarmolov, any update on this?

[tarmolov]

Nothing was changed since https://github.com/tarmolov/git-hooks-js/pull/28#issuecomment-259950000

However, maybe husky works better for you. It is supported GIT_STDIN variable which you're looking for. https://github.com/typicode/husky/pull/253

[getsnoopy]

Thanks, I'll look into it.