List of improvements for report

[benediktkr]

Fix some small errors in lokun-report

• Check if lokun.conf and lokun-tcp.conf exist and report errors. Now it just crashes if they are missing.
• Use the OpenVPN management interface to check if the service is operating correctly. Include in selfcheck? (See Use the OpenVPN management interface to check if the service is operating correctly. #29)
• Report total used bandwidth for that month. Then record will compare with max_bandwidth and disable a server that is running out of bandwidth. (See Max_bandwidth and max_usercount #20 )
• Use psutil for network throughput: https://github.com/giampaolo/psutil#network

[benediktkr]

• Do not count UNDEF users
• Add UNDEF users to selfcheck