monitoring: protocol: use error field to find errors
monitoring: protocol: use error field to find errors

result got overloaded to have errors in it. Don't do that. Instead check
the error field.

kaustavha/rackspace-monitoring-agent,christopherjwang/rackspace-monitoring-agent,cp16net/virgo-base,kaustavha/rackspace-monitoring-agent,cp16net/virgo-base,virgo-agent-toolkit/rackspace-monitoring-agent,christopherjwang/rackspace-monitoring-agent,cp16net/virgo-base,AlphaStaxLLC/rackspace-monitoring-agent,AlphaStaxLLC/rackspace-monitoring-agent,cp16net/virgo-base,virgo-agent-toolkit/rackspace-monitoring-agent,cp16net/virgo-base