Also support getOwner on all Unixes as they all have `Stat_t.{U,G}id`
Fixes #2552 Not needed when hardlinking. Only adds Linux support but other OS's may be easy.
Fixes an issue where the Ruby runtime expects the sticky bit to be set on the temp directory. The sticky bit is commonly set on the temp directory since it is usually shared by many users. This change brings ours in line with that assumption.
* Refactor AllocDir to have a TaskDir struct per task. * Drivers expose filesystem isolation preference * Fix lxc mounting of `secrets/`
