Merge pull request #152 from pamod/mqtt_dev

MQTT Code Re factoring
Fix infinite loop when delivering MQTT messages.
Merge pull request #153 from akalankapagoda/InfiniteLoopFix

Fix infinite loop when delivering MQTT messages.
Fix null pointer on decrementMessageCountInSlotAndCheckToResend for topics.
debug logs modified
changed a comment
Merge pull request #155 from sajinidesilva/refactor

Refactor
Merge pull request #154 from akalankapagoda/NullOnDecrement

Fix null pointer on decrementMessageCountInSlotAndCheckToResend for topi...
issue fixed in cql range query
Merge pull request #156 from indikasampath2000/performance

issue fixed in cql range query
Did changes on code review onFlight. Made todos.
excuted suggestions made at code review.
Merge pull request #157 from abeykoon/topic_code_review_changes

Topic code review changes
Removed 1. nodeQueues 2. GlobalQueues 3. QueueAddress 4. TopicDeliveryWorker 5. Unnecessary column families created by CQL Message store.
Merge pull request #158 from abeykoon/remove_nodeQ_globalQ_TopicDeliveryWorker_queueAddress

Remove GlobalQueues and NodeQueues
Removing the topic prefix which is appended to the node queue name.