initial draft for external metrics service
Merge branch 'dev' of github.com:etishor/Metrics.NET into dev

Conflicts:
	Src/Metrics/Visualization/MetricsHttpListener.cs
add internal error meter
add cpu count to environment data
add more performance counters
add more predefined units
add more samples
add method for scaling factor between time units
move value scaling to ValueSource instead of consumers
meter and timer values store the time unit they represent
remove remote registration for now
log error if remote metrics can't be updated
basic central metrics service
use correct path for v2 json in nancy
use different names and ports in samples to ease consumption by metrics central service