Revert "Temporarily disable IPC NS unsharing (prevents LVM deadlock)"

This reverts commit 672ef00332c379fa8e80060c8e668c6d7288207b.

Conflicts:
	py/mock.py
Restore IPC namespace when manipulating LVM

LVM uses semaphores for synchronization and to prevent deadlocks it is necessary
that all LVM manipulating commands are executed within global IPC namespace
and not in the one mock uses after unshare call.