vm-creator: Account for when we fail to detect an OS as "installed"
When Boxes fails to detect that an operating system has been installed (due to user interference or because something changed in the operating system and we haven't yet pick up the changes in our OS database), it keeps the OS in the "installation" state (which is the case for this bugzilla [0]) because the number of reboots performed is different than the number of reboots necessary for this OS to be installed. This is the bug. The logic shouldn't be whether the number of reboots performed is equal than the number of reboot necessary to install, instead, the logic should be whether the number of reboots performed is bigger than the number of reboots necessary for the installation to be concluded.