Added a framework for metrics

Added a metrics framework based on the codahale Metrics
package.  ONOS can create a registry and maintain Metrics,
as well as dump out metrics values via a REST API.  Unit
tests are include that test the REST APIs.  Currently
supports Timers, Counters, Gauges, Meters, and Histograms.

Change-Id: I0f6ed87f889dc7037caf9aefc92e663702c6dda8
diff --git a/conf/onos.properties b/conf/onos.properties
index c8509cf..a19cee5 100644
--- a/conf/onos.properties
+++ b/conf/onos.properties
@@ -5,7 +5,8 @@
 net.onrc.onos.core.flowprogrammer.FlowProgrammer,\
 net.onrc.onos.core.intent.runtime.PathCalcRuntimeModule,\
 net.onrc.onos.core.intent.runtime.PlanInstallModule,\
-net.onrc.onos.core.registry.ZookeeperRegistry
+net.onrc.onos.core.registry.ZookeeperRegistry, \
+net.onrc.onos.core.metrics.OnosMetricsModule
 net.floodlightcontroller.restserver.RestApiServer.port = 8080
 net.floodlightcontroller.core.FloodlightProvider.openflowport = 6633
 net.floodlightcontroller.core.FloodlightProvider.workerthreads = 16