closes #239.

Origin patch in PR-286.

client (worker) thread completing via a CountDownLatch.

Fixes #316

(trailing whitespaces, 2 spaces instead of tabs and e.t.c)

* returncodes -> OneMeasurement
* HashMap -> ConcurrentHashMap

Closes gh-353

As a part of branching to stage 0.2.0 release in #266, set version
for continued development on master branch.

- Make status interval configurable

- Output old histogram or HdrHistogram or both
- Potentially output HdrHistogram to log file on status interval.

Add a joined histogram measuremement to compare old/new histogram
outputs.

Add option for controlling the feature(default on).

Remove needless synchronization by using CHM in Measurements.

Add option to randomize delay(default=true, as before)

throttle method in client.

 [exporter] added JSONArrayMeasurementsExporter which generates one JSON array of measurement objects.

Given the min and max parameter ZipfianGenerator  should not return 0 if (uz < 1) nor 1 if (uz<1.0+Math.pow(0.5,theta)). Instead it should return the min value (base) or min + 1.

* Need a SNAPSHOT version because non-SNAPSHOT is reserved for actual releases.
* Increment minor version per pre-1.0 guidelines from the Version Numbers guide

Fixes #236.

closes #237.