add metrics for ExecutorService and ThreadFactory
'wrappee' sounds silly, renaming
add javadocs for java.util.concurrent instrumentations
implement ExecutionService instead of inheriting from AbstractExecutionService
rename underlying implementations as 'delegate'
use MetricRegistry#name instead of doing concatenation manually
use a Meter for completed tasks
make Metric members private and retrieve them from the registry for testing
format to adhere to project code convention
mark fields as final, removed a stdout statement
use meters for 'created' and 'finished'/'terminated' metrics
have both test classes terminate the generated threads cleanly
Fix handling of async requests.

Fixes #435. Closes #436.
Fix Counter javadoc.

Closes #434.
Alter Cormode paper link
Make documentation link to Cormode paper
Added new constructors to HealthCheckServlet and MetricsServlet

Making it possible to assign registries via constructor rather than via
ServletConfig.
Useful for programmatic embedding and test scenarios.
Add CORS Access-Control header.

Have the MetricsServlet send back the Access-Control-Allow-Origin header
so that the JSON output from the metrics servlet can be used in browser
based dashboards separate from the application.
Fix Gauge javadoc

The gauge docs incorrectly list value instead of getValue
Add test for Meter EWMAs approximation