* update mongodb-java-driver to latest 3.6.3
* add snappy for mongodb networkCompressor support

[core] Fixing squid:S1319 -  Declarations should use Java collection interfaces such as "List" rather than specific implementation classes such as "LinkedList".
(manolama - updated bindings added since the PR)

Signed-off-by: Chris Larsen <clarsen@yahoo-inc.com>

closes #798

- define checkstyle configs in as few places as possible
- use checkstyle:check since it has defaults that match what we want (fail after logging to console)
- modules that have current failures set property checkstyle.failOnViolation to false.

[mongodb s3 tarantool] Fixing common-java:DuplicatedBlocks - Source files should not have any duplicated blocks

This ensures that users do not confuse the results from batched
and non-batched operations.

Closes #522

Replaces numeric status codes with a canonical set of Status objects,
each with a short name and description.
Bindings with more specific errors (e.g., timeouts) return additional
statuses.

This changes the default output from messages like:

   [UPDATE], Return=0, 511

To:

   [UPDATE], Return=OK, 511

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.

Updated code to satisfy the checkstyle validation.

Fixes #365

In order to get the tests to pass again, reverted MongoDbClient to use update with upsert instead of insert when batch size is 1.

Added journal=true back into MongoDB connection string.  For now, the connection string will contain both "j" and "journal", until such time as the MongoDB Java driver supports "journal".

Simplified insert CRUD code to always use insertMany even when batchSize == 1,
 as there is no performance penalty for this in the driver.

Changed visibility of static field from protected to private in final OptionsSupport class for MongoDB.

Changes:
1. mongodb configuration parameter bug (mongodb.url)
2. README file change
3. Some cleanup. Default DB is 'ycsb'