Add metrics

- Work in progress added Heka message protobuf logging
- Instrumented HistogramCache as the initial test
Merge branch 'master' into metrics

Conflicts:
	common/HistogramCache.cpp
	convert.cpp
Merge branch 'master' into metrics

Conflicts:
	common/CMakeLists.txt
	common/HistogramCache.cpp
	common/HistogramCache.h
	convert.cpp
Add basic metric data for each component
Merge pull request #4 from trink/metrics

Metrics