HBASE-12337 Import tool fails with NullPointerException if clusterIds is not initialized
HBASE-12471 Task 4. replace internal ConnectionManager#{delete,get}Connection use with #close, #createConnection (0.98, 0.99)
HBASE-12449 Use the max timestamp of current or old cell's timestamp in HRegion.append()
HBASE-10378 Refactor write-ahead-log implementation

Incompatible changes called out in release notes on jira.

* Cleaned up references to HLog
* Deprecates HLogKey but maintains it for compatibility
  - Moves all Writeable from WALKey to HLogKey
* Adds utility code to CoprocessorHost to help with evolving Coprocessor APIs
* RSRpcServices roll WAL call now requests the non-meta LogRoller roll all logs
  - rolls actually happen asynchronously
  - deprecated old api (and noted incompatible behavior change)
  - modified api in new Admin interface to reflect lack of return values.
* Moved WAL user facing API to "WAL"
  - only 1 sync offered
  - WALTrailer removed from API
* make provider used by the WALFactory configurable.
* Move all WAL requests to use opaque ids instead of paths
* WALProvider provides API details for implementers and handles creation of WALs.
* Refactor WALActionsListener to have a basic implementation.
* turn MetricsWAL into a WALActionsListener.
* tests that needs FSHLog implementation details use them directly, others just reference provider + factory
  - Some tests moved from Large to Medium based on run time.
* pull out wal disabling into its own no-op class
* update region open to delegate to WALFactory
* update performance test tool to allow for multiple regions
* Removed references to meta-specific wals within wal code
  - replaced with generic suffixes
  - WALFactory maintains a dedicated WALProvider for meta (and so knows about the distinction)
* maintain backwards compat on HLogPrettyPrinter and mark it deprecated.
  - made WALPrettyPrinter IA.Private in favor of `bin/hbase wal`
* move WALUtil stuff that's implementation specific to said implementation
  - WALUtil now acts as an integration point between the RegionServer and hte WAL code.

Incorporates contributions from v.himanshu.

Signed-off-by: stack <stack@apache.org>
    HBASE-10378 Refactor write-ahead-log implementation -- ADDEDNUM
HBASE-12515 update patch tester to use git

Signed-off-by: stack <stack@apache.org>
HBASE-12411 Optionally enable p-reads and private readers for compactions.
HBASE-12421 Clarify ACL concepts and best practices

Signed-off-by: stack <stack@apache.org>
HBASE-12495 Use interfaces in the shell scripts (Solomon Duskis)
HBASE-12517 Ensure HConstants members are final.

Signed-off-by: stack <stack@apache.org>
HBASE-12513 Graceful stop script does not restore the balancer state

Signed-off-by: stack <stack@apache.org>
HBASE-12496 A blockedRequestsCount metric (Yi Deng)
HBASE-10560 Per cell TTLs
HBASE-12174 MR support for cell TTLs