Fallback support for inactive socket

The main goal is to allow any user (even if he/she hasn't installed or forget to start ponyd) to be able to still debug any part of the code.

The new few lines make a check about the socket activity and route the output between Ponydebugger and classic NSLog
White Style: `NSLog(@"%@", arguments);`

I think there should be a prefix appended so it's clear that PDLog() was being called. Something like: 

`NSLog(@"PDLog: %@", arguments);`