This is common operation that is repeatable.
Common functions that revolve around running the tool (like `dont_run_as_root`) will be methods of this class.
This is part of fixing qvm-start. qmemman was moved with minimal touching, mainly module names. Moved function parsing human-readable sizes from core2. This function is wrong, because it treats k/M/G as 1024-based, but leave it for now.