In OneMeasurementHdrHistogram, now reading hdrhistogram.percentiles
from workload configuration. This property is a comma delimited string
of Integers to use as percentile values.

This implements #437

size for the window so a mask can be used instead of a modulo operation.
This avoids issues when there is overflow of the id integer values to
negative values.

The HdrHistogramReader makes some problematic assumptions on the roles
played by start time, base time and histogram start/end times. This is
to be revisited in a future release of HdrHistogram (see
https://github.com/HdrHistogram/HdrHistogram/issues/69). In the meantime
this change will make YCSB record as expected by the reader:
a. Set histogram log base time (same as start time)
b. Only create the recorder after the log has been setup

final, refactor repeated export code from subclasses.

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

- 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.