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
Clarified documentation on context listener.

MetricsServletContextListener does not instantiate any registries of its own, it merely injects provided registries into the servlet context.
Change the timing for ScheduledReporterTest.

Hopefully some improvement for #413.
Merge pull request #414 from TomRK1089/master

Clarified documentation on MetricsServletContextListener.
clarify the VisualVM plugin to use for viewing JMX MBeans
Merge pull request #415 from zathomas/master

clarification on the VisualVM plugin to use
avoid intermediate checks of Mockito
Clarify the docs.
Clarify metrics-servlet.