[MERGE] Added support for a hook before sending the commit message to the editor.

[Alexander Belchenko]

Alexander Belchenko has voted comment.
Status is now: Waiting
Comment:
why for it's needed?

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C20c6e49023f4afd62951c0da6944be7a%40localhost%3E