Adding abort and interrupt signal handling for long running mode.

[JeffreyLMelvin]

chopshop

• added signal handler for abort signals
• passed sigint to surgeon and nids processes

ChopLib.py

• stored surgeon in choplib object so is accissble from chopshop
• added handler for abort and interrupt in nids process

ChopNids.py

• handling of abort and interrupt variables in core to exit nids appropriately

ChopSurgeon.py

• added handler for abort and interrupt in surgeon process
• removed longrun from surgeon_proc_list function b/c it is no longer used
  • needed to use self.long to update the variable in the signal handler
• added stopread to self so could be set in signal handler