Remove log4j as a dependency

This prevents jrugged from leaking a potentially unwanted log4j
into end users' projects as a transient dependency. This is
especially pesky when an alternative logging implementation is
desired.
Remove EmptySampleSetException in favor of return 0

Addresses Issue #6 on Comcast/jrugged.  Instead of returning an
EmptySampleSetException if calling getQuantile or getPercentage when
there's no data for the time span, return 0, which is friendlier to
humans and machines both.
Add service name to RolledUpMonitoredService reasons.

If a RolledUpMonitoredService has a status that is not UP then
getReasons can be used to determine the cause.  Calling getReasons()
enumerates the reason for each child service that is not UP.  In
many cases the child services are CircuitBreakers.

The current behavior for getReasons() lists only 'Open' or
'Send Probe Request' for each CircuitBreaker.  It does not include
any identification for which CircuitBreaker is affected.

This change adds the service name as a prefix for each reason,
making it clear which service is causing the Non-UP status for the
RolledUpMonitoredService.

Before Change:  getReasons() might return
  { "Open", "Send Probe Request" }

After Chnage: getReasons() might return
  { "Service 1:Open", "Service 2:Send Probe Request" }
Change the javadoc to reflect the new status - that returns the NAME of the service with the reason it has a particular up, degraded, down status.
refer to the correct APIDOCS location for jrugged API documentation.
[maven-release-plugin] prepare release jrugged-3.1.0
[maven-release-plugin] prepare for next development iteration
Update README.md

Adding a new release information.
Update README.md

Bad title on the java doc section of the README
Update README.md

Low and behold github removed the downloads area... foo, bar, baz!