util: add an option for configuring break length

This commit adds a breakLength option to util.inspect(). This
option allows users to control the length at which object keys
are split across multiple lines. For backwards compatibility,
this option defaults to 60.

Fixes: https://github.com/nodejs/node/issues/7305
PR-URL: https://github.com/nodejs/node/pull/7499


Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>