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.
Merge pull request #159 from pamod/mqtt_dev

Removing the topic prefix which is appended to the node queue name.
code cleanup.
Comments added.
Merge pull request #160 from Asitha/code-cleanup

Code cleanup
Documentation errors fixed
Introducing the path to handle acks received for QOS 1 and 2.
Merge pull request #162 from pamod/mqtt_dev

Introducing the path to handle acks received for QOS 1 and 2.
Merge pull request #161 from Asitha/code-cleanup

Documentation errors fixed
MQTT Perf Enhancments, changing logging in the MQTT library, Renaming QueueDeliveryWorker to MessageFlusher
Merge pull request #163 from pamod/mqtt_dev

MQTT Perf Enhancments, changing logging in the MQTT library, Renaming Qu...
Refactor code and fix a spelling mistake
Merge pull request #165 from a5anka/refactor

Refactor code and fix a spelling mistake
MQTT Perf improvments, adding synchronous message delivery, changing the enum definition of MQTT lib
further refactoring - adding context to logs, missing comments