README.md: fix instructions for building and tests
README.md: fix instructions for building and tests

Code was changed without updating the documentation for building or for
running new entry points. Fix this.

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