inspector: change default port

We should use a different default port number for the new debug
protocol. This makes it easier for debuggers to guess which protocol
they are expected to use to talk to a node process with a debug
server.

PR-URL: https://github.com/nodejs/node/pull/7212


Reviewed-By: bnoordhuis - Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: cjihrig - Colin Ihrig <cjihrig@gmail.com>