Handle division by zero when no tcp datagram was sent or received between metrics collection
Handle division by zero when no tcp datagram was sent or received between metrics collection

NoodlesNZ/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,fastly/monitor-core,fastly/monitor-core,fastly/monitor-core,phreakocious/monitor-core,lawrencewu/monitor-core,phreakocious/monitor-core,fastly/monitor-core,lawrencewu/monitor-core,lawrencewu/monitor-core,lawrencewu/monitor-core,torkelsson/monitor-core,phreakocious/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,fastly/monitor-core,NoodlesNZ/monitor-core,sdgdsffdsfff/monitor-core,mjzhou/monitor-core,lawrencewu/monitor-core,ganglia/monitor-core,lawrencewu/monitor-core,phreakocious/monitor-core,torkelsson/monitor-core,ganglia/monitor-core,phreakocious/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,sdgdsffdsfff/monitor-core,torkelsson/monitor-core,lawrencewu/monitor-core,fastly/monitor-core,mjzhou/monitor-core,phreakocious/monitor-core,mjzhou/monitor-core,ganglia/monitor-core,phreakocious/monitor-core,torkelsson/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,ganglia/monitor-core,ganglia/monitor-core,NoodlesNZ/monitor-core,torkelsson/monitor-core,sdgdsffdsfff/monitor-core,NoodlesNZ/monitor-core,mjzhou/monitor-core,sdgdsffdsfff/monitor-core,mjzhou/monitor-core,torkelsson/monitor-core,torkelsson/monitor-core,fastly/monitor-core,sdgdsffdsfff/monitor-core