Do not make daemon output zero byte

This byte is useless and can be seen in zsh output (strange that it did not 
cause bugs so far, at least none I know about). It may have been needed if any 
client was supposed to hold connection with daemon for a few runs, but all 
current clients work in “request → output response → exit” fashion without 
caring about terminating newline and definitely without preserving connection to 
daemon accross runs.

@kovidgoyal Please reply if you had any specific reason to add this zero byte, I may revert this and modify clients instead.