cocrrected debug log
change type of arrival time to primitve Long to avoid NPEs
Fixing the issue encountered when un-subscribing from an MQTT topic
Merge pull request #147 from hastef88/queue_purge_feature_refactor

change type of arrival time to primitve Long to avoid NPEs
Merge pull request #148 from pamod/mqtt_dev

Fixing the issue encountered when un-subscribing from an MQTT topic
Merge pull request #146 from sajinidesilva/debug

corrected debug log
Adding licence headers, adding functionality to rollback during an exception occurs when adding the subscribers
Merge pull request #149 from pamod/mqtt_dev

Adding licence headers, adding functionality to rollback during an excep...
issue fixed in trying to deliver already bufferred message
Merge pull request #150 from indikasampath2000/performance

issue fixed in trying to deliver already bufferred message
refactored slot based modifications
Merge pull request #151 from sajinidesilva/refactor2

refactored slot based modifications
Refactoring code, adding ability to handle acks in MQTT
MQTT code refactoring
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