Add Suspending/Resuming ASG Processes to ELBv2

[tgroshon]

The ELBv2 example scripts do not support suspending and resuming troublesome ASG processes but the original ELB scripts do.

Update the ELBv2 common_functions.sh file to add this functionality.

• Add a HANDLE_PROCS variable that denotes whether to suspend processes; defaults to false
• Add a FLAGFILE implementation to keep track of which processes were suspended during the deploy and should be resumed
• Update ASG decrementing to use the FLAGFILE instead of the single 'flag file'
• Update the README.md to explain the ASG process suspension use case

Fixes Issue #53

[tgroshon]

@avalent yessir, Apache v2.0 is good with me 😄

[tgroshon]

Thanks you guys!