HFX-990: Install vhd-tool on legacy path for backport

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Update ocaml-vhd to 0.6.1

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
CA-120439: Update to vhd-tool 0.6.1

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
CA-120439: Update to vhd-tool 0.6.2

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
CA-120525: Update to vhd-tool/ocaml-vhd 0.6.3

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Update to vhd-tool 0.6.4

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
CA-120549: Update to ocaml-vhd 0.6.4

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
CA-120549: Bump release of vhd-tool RPM

This has now been compiled against some fixes in ocaml-vhd 0.6.4.

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Merge pull request #1 from xapi-project/hfx-990

[HFX-990]: Merge in new vhd-tool package (sparse_dd)