Partition resize script needs updating to work with latest images

[ndorf]

#Hello,

I've successfully used your work to flash my new BeagleBone with the latest Debian 9 images, here and here. Thank you, it was much more convenient than having to use a microSD card!

To work with these new images, I had to change just a few a characters in the script. The commit log should explain it all, but the short version is that these images only have one partition (the root, with /boot as just a subdirectory). It seems that the script was expecting to modify the second of two partitions, and corrupted the partition table as a result.

And I changed the status message, just because there were typos, and I think it's less confusing now (even on my 4GB BeagleBone, resizing made available an additional ~250MiB that was left over after flashing). Obviously, you can decide. The patches are submitted for your consideration. Thanks!