Support Node 8

[ewindisch]

This is now built in although considered experimental:
https://nodejs.org/api/inspector.html

[ewindisch]

Briefly discussed with @coreylight for fidelity and it seems with this we'd create a v1 branch of the current code to support Node v6.10. Then, we'd maintain master off the new node stdlib inspector module.

[ewindisch]

Work in progress branch: https://github.com/ewindisch/iopipe-plugin-profiler/tree/node8

I expect this should be ready for become a PR within a couple days!

[ewindisch]

Addressed by #49

[ewindisch]

Branch with continued work to attempt getting heap profiling working. This has a bunch of wolf-fencing and other things built-in (as of writing this), and is non-working... so I didn't want to commit it to the otherwise working 'node8' branch: https://github.com/ewindisch/iopipe-plugin-profiler/tree/node8heap