Attempt to retrieve the vmdk descriptor data-pair

VMDK formats such as monolithicFlat and vmfs require two files to be
fully consumable by the Nova drivers (a descriptor-data pair: *.vmdk and
*-flat.vmdk).
On the upload of the descriptor (*.vmdk), upload_image.sh should attempt to
retrieve the *-flat.vmdk. The same way, the descriptor should be
retrieved when a flat disk is uploaded.
On success, the upload script will be able to use the flat disk as the image
content and the relevant descriptor settings as the image metadata.

Change-Id: I9214754029c46dd60b9e7d606d84d8819a498a8d
Closes-Bug: #1252443
Merge "Attempt to retrieve the vmdk descriptor data-pair"
xenapi: enable user interaction with stack.sh

In XenServer, devstack runs inside a virtual machine. This makes it hard
for the user to interact with stack.sh should a parameter be missing.
This change will create an upstart job (devstack) that runs
stack.sh with console enabled so user can interact with it by running
vncviewer or using XenCenter.

Logging the output is also disabled, stamp files are used instead to
detect the script run status in case install_os_domU.sh is used.

As run.sh.log is removed, standard devstack logging should be used.

The change also removes the environment settings from run.sh, as they
are not needed, they should be specified in localrc. This way user
cannot get different experiences by using unstack.sh/stack.sh or run.sh

Also a proper unstack.sh is called instead of killing screen in run.sh

Change-Id: I7eb12bd74746cc7a1db3aa9fd68ece645a50001d
xenapi: display IP and DevStack result on console

The devstack setup service can update /etc/issue, displaying the status
of the installation and the VM's management IP. With this change, after
the devstack service finsihed, the login prompt will look like this:

OpenStack VM - Installed by DevStack
  Management IP:   10.219.3.108
  Devstack run:    SUCCEEDED

DevStackOSDomU login:

This helps people to log in to their system.

Change-Id: Idd6bbd5faf9ced5618cd3e95191bfc3b89473fa2
XenAPI:  Increase DomU's memory

Devstack has been increasing in complexity, and if we use too
much of our memory it can lead to fragmentation which in turn
causes a DomU error and a failure of random tests.

Change-Id: Ide9cc84625caed4e35a64a47ee1e92a6cd567651
XenAPI: Update DomU to Ubuntu Saucy

Driven by a race condition in LVM being hit in the tempest
tests.  This is a locking race between a file lock and a
semaphore which is fixed in 2.02.96-5.

Change-Id: I8a8c215c90a0602288292ffd06b7694d2db6219e