Change frameserver warnings to debug level 2

[knight-of-ni]

Low priority pull request. This provides a way to get feedback from the logs when troubleshooting the frameserver.
Level 2 was arbitrarily chosen.

[mastertheknife]

A level of 4-6 would have been better because we don't want to flood the logs for each frame.

[knight-of-ni]

@mastertheknife Thanks for the feedback.
Changed the three events to debug levels 4,5, & 6 respectively.
Generally speaking, are there a loose set of rules for choosing debug levels?

[mastertheknife]

There isn't a guideline, just need to look at the source code of ZM to get some idea what debug level should be used.