#19 Configurable action on autosave

[Mark Baaijens]

Saving VM state may not be desirable for all users, as starting guests in a clean state is generally preferable.

For this, new setting in /etc/vboxtool/vboxtool.conf must be implemented: autosave_command.
This can be the following:
- save (default)
- stop (= VBoxManage poweroff)
- softstop (VBoxManage acpipoweroff)

Note. The 'softstop' command is not implemented right now, see feature request 239993: https://sourceforge.net/tracker/?func=detail&aid=2794028&group_id=239993&atid=1111632