Check-paloalto

------------------
* Fixed issue 8: Measuring throughput on multiple identically configured PA's fails

------------------

* Improvement: It is no longer necessary to reset the internal cookie when upgrading PA.
* Renamed performance data label for throughput command.
* Removed the the unit of measurement (UOM) for throughput command

----------------

* Support for Python 3.5 added
* Minor code improvements
* Changed the the unit of measurement (UOM) according to official Nagios-Documentation (thanks to Ios77)

------------------

* Added script version switch
* Improved error handling
* Updated documentation
* Upgraded dependencies

------------------

* Fixed a argparse bug

------------------

* Added functionality to monitor state of the user-agents
* Added script timeout switch
* Improved error handling
* Improved functionality of sessinfo command