Upgrade to v0.11

The V8 API has changed a great deal.  Update strong-cpu-profiler
accordingly.

Notable changes to the strong-cpu-profiler include the removal of the
following functions and properties:

  * CpuProfile#getBottomUpRoot()
  * CpuProfileNode#selfSamplesCount
  * CpuProfileNode#selfTime
  * CpuProfileNode#totalSamplesCount
  * CpuProfileNode#totalTime

Their corresponding V8 methods have disappeared with no real
replacement.

Suggested reviewer: @rmg and @themitchy?  If I read the strong-agent code base right, none of the eliminated functions were being used but I'd like you guys to confirm that.

This should probably be parked in a separate branch until we drop v0.10 support.  Either that or we create a v0.10 maintenance branch and make master target v0.11/v0.12.