[core] Record latency of successful and failed operations separately

[core] Added variance calculation of histogram latency reporting.

[vcs] Added support for Vim and Emacs in .gitignore

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

Define constants for the property strings.

[googledatastore] Add a Google Datastore client

- Move the doc (code comment) to workload_template
- Minor changes in propery parsing logic and log to System.Err;

[core] Incoporate CR comment

Missed one comment before.

And make it configurable.

Specifically:

1. Remove trailing spaces,
2. Replace TAB with spaces,
3. Break lines > 80 characters
4. Misc code alignment.

No functional code change. use ?w=1 on the URL to view non-whitespace changes.

Revert "added S3 storage binding"

[S3] added S3 storage binding

Closes #413 

Addressing the last CR comment.

[googledatastore] Add cause to DBException

Copyright statement, better exception messages, etc.

1. Move documentation from the properties file to the README.md
2. Addressed a couple of comments in the code.
3. Added the checkstyle plugin and addressed all the violation (except
the TODO comment violation. I'd like to keep a TODO item in the code).

[googledatastore] Output debug logs in one line instead of multiple lines.

Will implement scan separately in the next pull request.

Add support to allow users to group entities in two different ways, and add documentations for the overall googledatastore.properties file.

Add a DB client for Google Cloud Datastore. This initial commit includes implementation of all CRUD operations (modulo scan), and integration into the rest of YCSB (pom.xml changes, etc)

Next few commits will include Scan/query support, single entity group support, and better documentation.

[elasticsearch] Checkstyle updates for Elasticsearch.

[redis] Checkstyle updates for the Redis binding.

[voldemort] Update binding to use the new Status class and also checkstyle updates.

[core] passing full fieldset for verification

When dataintegrity and readallfields are both true, pass the full field
set to db.read() so that the field values can be verified.

Fixes #496

[core] added return codes to VERIFY

[jdbc] removed semicolons from cached statements

Changed measurement latency to actual latency time of the verifyRow step
and now recording Status codes for verify operations.

Fixes #479

[kudu] Checkstyle updates for the Kudu binding.

[hbase10] Checkstyle updates for HBase 1.0 binding.

checkstyle updates.

Closes #477. This is #477 rebased against current master, with long
lines in commit messages wrapped.