Microsoft helpfully removed the PackageDir property from package projects
in VS2015 so, as an interim fix, OutDir was used. This unfortunately means
that package output ends up in xencons/<arch>/package rather than just
xencons/<arch>.
This patch fixes the final package location by using python to do the
final copy (replacing what older VS used to do) and also adds a BUILD.md,
which was missing.
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>