monitoring: tests: catch top level errors
monitoring: tests: catch top level errors

AgentClientConnection now throws errors if it encounters one. Ensure the
unit tests that expect errors catch this to avoid throwing a top level
error.

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