CLI reference added

A new chapter was recently added to the book. It proposes a reference for the symfony Command Line Interface (CLI) and it should help those who need more than what the symfony -T command returns.

And even before we mention this chapter here, someone already translated it in Japanese! We are very pleased to open the comprehension of symfony to non english speakers. Remember that if you want to write a custom documentation for symfony, even in another language, the symfony wiki is probably the best place to make it public.