util: prepend '(node) ' to deprecation messages

util: prepend '(node) ' to deprecation messages

Changes included in this commit are

   1. Making the deprecation messages consistent. The messages will be in
      the following format

           x is deprecated. Use y instead.

      If there is no alternative for `x`, then the ` Use y instead.` part
      will not be there in the message.

   2. All the internal deprecation messages are printed with the prefix
      `(node) `, except when the `--trace-deprecation` flag is set.

Fixes: https://github.com/nodejs/io.js/issues/1883
PR-URL: https://github.com/nodejs/io.js/pull/1892
Reviewed-By: Roman Reiss <me@silverwind.io>