Added in V8::C::Debug::EnableAgent()

Also adding in some quick documentation.  Let me konw if there's any issues with the code!  Seemed like a pretty simple addition.

I still haven't been able to use Eclipse for anything interesting.  It crashes 80% of the time.  And when it's not crashing, it doesn't show any detailed information on the stack, variables, or file sources.  I haven't had much luck with jamming JSON into my telnet client either.

Attempting something like ```{"seq":725,"type":"request","command":"setexceptionbreak","arguments":{"type":"all","enabled":true}}``` doesn't seem to have any effect.  Any suggestions?