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

[core] Update the AcknowledgedCounterGenerator to use a power of two and mask.

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.

[mongodb] Add mongodb.upsert configuration option.

Added a configuration option (mongodb.upsert) to control if the driver
performs inserts or upserts operations for the DB.insert() method.
Defaults to doing inserts.

Note: Change in behavior from previous versions that performed upserts
for non-batched DB.insert() operations.

Fixes #400.

[redis] Fix the label for a redis parameter

host, not url.

[cassandra-cql] Make CassandraCQLClient more consistent.

The CassandraCQL client defines a number of

* Changes the default port to 9042 (this is the default CQL port).
* Changes property "host" from a space-separated list to property
  "hosts", a comma-separated list.
* Updates a few messages.

Use a PageFilter in HBase scans

Via `hbase.usepagefilter`

Other bindings limit the number of results retrieved from the server.
The HBase bindings just close the scanner once they have received the
desired number of records. Adding a PageFilter matches the behavior of
other bindings, and may improve performance.

[aerospike] Bring Aerospike adapter in line with adapter policy

* ! Aerospike client no longer retries over errors
* ! Aerospike client no longer backs off during cluster overload

Proposed fix for #327.

[hbase10] Add integration tests for HBase 1.0 client

Uses an HBase mini-cluster to test the HBase binding.

[docs] update README for 0.3.1 release.

[hbase] Separate HBase v0.9x and v1.x bindings

Remove deprecated methods:
Put.add -> Put.addColumn.
KeyValue -> Cell.

HBase 0.94 requires an additional dependency on hadoop-core, but has no
source-level changes to the client.

hbase/ now contains the HBase v0.9 binding code.
hbase1/ now contains the HBase 1.0 binding code.

- *incompatible* Default measurement changed from histogram to hdrhistogram
  Users who want previous behavior can set the 'measurementtype' property to 'histogram'

- *incompatible* Reported 95th and 99th percentile latencies now in microseconds (previously in milliseconds)

Conflicts:
	core/src/main/java/com/yahoo/ycsb/measurements/OneMeasurementHdrHistogram.java

closes #371

[docs] Fixes #393 - Update the curl command to use the --location option

[travis] Fixes #389 - Update .travis.yml to use the container based infrastructure for Travis Builds.

[travis] Fixes #389 - Update .travis.yml to use the container based infrastructure for Travis Builds.

[docs] update README for 0.3.0 release.

Added ASLv2 header to most files missing one.