[Release] Update top level README.md file to point to 0.9.0 release.

[elasticsearch] Bump version to 2.3.2

This commit bumps the version of the Elasticsearch dependency for the
Elasticsearch binding to version 2.3.2.

[couchbase2] Better Defaults & Scan Refactor

[riak] Added a workaround to allow strong-consistent scan transactions.

[bigtable] Bigtable uses 1ms granularity.

Fixes #733

[core] Add the Utils.getGCTotalTime() method for showing how long

collector. This will allow greater insight into the generations.
Now the client will emmit the stats for each collector at the end of
run along with the totals.

the JVM spent in GC. It now prints the time and percent of time in
the final output.
Also fix cases where the garbage collector implementation returns
-1 if the count or time isn't implemented.

[core] add operation tracing via Apache HTrace.

[scripts] Fix bin/ycsb for Python 2.6 and bin/ycsb check_output

[geode] Update geode binding for v1.0.0-incubating.M2

This changeset refactors the scan operation slightly, using a List
with a predefined size (since we know it), as well as using the
document ID directly for the response rather than doing full blown
JSON decoding which is not needed.

This changeset picks better default settings for the environment
to make it less error-prone in cloud setups and in turn leads to
easier usability.

The changes made are:

  - queryEndpoints set from 5 to 1 by default since this is technically
    a leftover from earlier implementations. We now have a Bucket per
    Thread and since YCSB is sync anyways we only ever need one. Leaving
    it as an option since if we get async ops in the future we can utilize
    those.

  - socketConnectTimeout from 1s to 10s, especially in cloud environments
    socket timeouts are annoying and its better if we have higher defaults.

  - connectTimeout changed from 5s to 30s since the socket connect timeout
    is higher we also need to adjust this one.

  - kvTimeout changed from 2.5s to 10s so that under throughput saturation
    testing you don't get flooded with timeouts potentially. Note that it
    also makes for nicer output if you get "higher latencies" as part of
    the regular output and not in the error section.

[elasticsearch] Return not found instead of error

[core] Add the "measurement.trackjvm" property to measure JVM statistics

[core] Parallel run and string sort order

Conflicts:
	core/src/main/java/com/yahoo/ycsb/workloads/CoreWorkload.java

fixed conflict, fixed extra spaces and space between methods

[kudu] Upgrade client dependency to Kudu 0.8.0