Trace kernel events in usermode session on Win8+

[ilabutin]

This is an attempt to address #549 and be able to run two PerfView on the same server. The code works (tested also on Win 7), but there are number of questions (TODO in the code) to address before it can be merged:

• circular buffer size (usermode vs kernel mode)
• user mode session name randomization
• buffer size calculation (with/without rundown)
• kernel mode session early disposal

I'd be happy to get any hints on these questions to address them and finalize this.

[vancem]

Thanks for attacking this. It is a non-trivial change, I will need a few days to take a proper look.

[felipepessoto]

This change would make possible to use PerfView without admin permissions?