Merge pull request #186 from pamod/mqtt_dev

Updating tracker before the message was release to the wire, avoid NullP...
Fix SSL Port binding.
Merge pull request #187 from akalankapagoda/sslconfig

Fix SSL Port binding.
msgId2MsgData map changed to ConcurrentHashMap and getMetaDataList changed to get batch records 1000 wise
Merge pull request #188 from indikasampath2000/performance

msgId2MsgData HashMap changed to ConcurrentHashMap and getMetaDataList changed to get batch records 1000 wise
Move message scheduled to deliver increment to set before thread.
Handle message DLC move exception.
Merge pull request #189 from akalankapagoda/incrementerUpdate

Move message scheduled to deliver increment to set before thread.
Add comment to explain logic behind getMetaDataList method
Merge pull request #190 from indikasampath2000/performance

Commenting on logic behind getMetaDataList method
refactored methods.
refactored enums related to cluster notifications.
updated licence header.
Merge pull request #191 from abeykoon/refactor_queue_delete

Refactor queue delete
Replace SequentialThreadPoolExecuter with DistruptorBasedFlusher
Merge pull request #192 from a5anka/disruptor_delivery_implementation

Replace SequentialThreadPoolExecuter with DistruptorBasedFlusher
Add cassandra consistency levels

Cassandra consistency levels for read write operations.
Only supports Cassandra below 1.2.x versions# Please enter the commit message for your changes. Lines starting
Fix Slot recovery bug in JDBC message stores

Reason for this was the CQL message store was returning results for
getNextNMessageMetadataFromQueue without  starting message while
JDBC message store returned with starting message.
Merge pull request #194 from a5anka/fix_slot_recovery

Fix Slot recovery bug in JDBC message stores
Moved methods in CassandraConstants class to GenericCQLDAO class