BulletSim: add adjustment for avatar capsule height scaling. Makes
avatar standing on ground view better and enables tuning.
BulletSim: add a lock to try and catch a native shape creation/destruction
race condition.
BulletSim: Fix for mantis 6487, also minor adjustment to fix flying while you are running.

Signed-off-by: Robert Adams <Robert.Adams@intel.com>
Eliminate race condition where SimStatsReporter starts reporting
stats before the region is completely initialized.