QOS=1,QOS= 2, MQTT 3.1.1 spec, re-connection base code + documentation.

The following merge request has the following features.

Support for QOS 1 and 2
Support for reconnection + resubscription(**)
MQTT and Library documentation on README.md
MQTT 3.1.1 as an optional protocol
3.1.1 Spec Tests executed on a MQTT 3.1.1 broker (http://wiki.eclipse.org/Paho/MQTT_Interop_Testing_Day)

I also sent an email with more detailed information.

Please let me know if you need information about some specific code or strategies that were implemented on this fork.