first cut at Rackspace upload functionality

Rackspace uses a task-based upload scheme that, as of the time of this patch,
is not part of upstream OpenStack.  To use it we have to make use of the
pyrax Python binding.

The "provider" in the case of Rackspace is expected to be one of the standard
rackspace region codes.  Known regions supported right now are:

ORD, DFW and SYD

On the Factory CLI these should be specified as @ORD, etc.
add missing vhd source
Initial cut at direct docker base image creation
update Rackspace RPM requires to include python-pyrax
add size calculation - add parameter to disable metadata wrap
change for Python 2.6 tarfile module compatibility
Merge pull request #343 from redhat-imaging/feature/docker-metadata-image

Feature/docker metadata image
Merge pull request #344 from redhat-imaging/feature/rackspace_upload_pyrax2

Feature/rackspace upload pyrax2
add support for configurable VirtualSystemType value in vsphere OVF support

The default value remains "vmx-07 vmx-08"

According to VMWare, this value can be a list of one or more vmx-## values
where the number corresponds to support for the following products:

10 - ESXi 5.5, Fusion 6.x, Workstation 10.x, Player 6.x
9 - ESXi 5.1, Fusion 5.x, Workstation 9.x, Player 5.x
8 - ESXi 5.0, Fusion 4.x, Workstation 8.x, Player 4.x
7 - ESXi/ESX 4.x, Fusion 3.x, Fusion 2.x, Workstation 7.x, Workstation 6.5.x,
    Player 3.x, Server 2.x
(earlier versions omitted)

Detalis taken from:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003746

This relates to BZ 1059456:

https://bugzilla.redhat.com/show_bug.cgi?id=1059456
Merge pull request #346 from redhat-imaging/feature/vmware_virt_hw_version_take2

add support for configurable VirtualSystemType value in vsphere OVF supp...
bugfix: spec post script error for Nova plugin