Changes

Create a virtual disk /dev/vda in centos2 and use that virtual disk (vda) instead of /dev/sda (so use '''fdisk /dev/vda ''' instead of using '''fdisk /dev/sda'''). This makes Lab 5 easier to handle accidental corruption students might make while doing that lab thereby destroying their centos2. This might require Lab 5 checker script to be tweaked to work with /dev/vda.