v2v: Remap device in /etc/sysconfig/grub boot= entry.

Old virt-v2v did not remap this device, so after conversion from Xen
the file would have something like:

  boot=/dev/xvda

Although this does not appear to affect anything, better to remap it.
tests: Add drivers directory to phony Windows image.

Allows virt-v2v to upload drivers.
v2v: tests: Don't care about the <model> XML when testing network and bridge mapping.
v2v: windows: Set filename correctly when uploading virtio drivers (RHBZ#1145916).

Thanks: Jeff Forbes, Alain Vondra, Junqin Zhou
v2v: Update list of virtio-win drivers to latest (RHBZ#1145908).

Update with latest list from:
- virtio-win-1.7.2-1.el7.noarch
- https://en.wikipedia.org/wiki/List_of_Microsoft_Windows_versions
v2v: Failure to mount the root partition is a hard error.

For other partitions, it is a warning.
v2v: windows: Give a better message when Fast Restart is found (RHBZ#1145995).

Thanks: Tingting Zheng