metrics: Add metrics target to top level Makefile
metrics: Add metrics target to top level Makefile

Now we have the basic framework in place and a single metrics
test running, add the 'metrics' target to the Makefile

Fixes: #85

Signed-off-by: Graham Whaley <95f36e5ac6982f4574a5c449c37cf652e934d2b9@intel.com>

GabyCT/tests,chavafg/tests,clearcontainers/tests,sboeuf/tests,devimc/tests,clearcontainers/tests,MarioCarrilloA/tests,MarioCarrilloA/tests,devimc/tests,GabyCT/tests,bwarden/tests,bwarden/tests,chavafg/tests,sboeuf/tests