Fix typo in property passed to glance

In the upload_image function, a property that is passed to glance in
the vmdk conditional block has a typo. Changes "vmware-disktype" to
"vmware_disktype" (dash to underscore)

Change-Id: I6c4e1875b6ab4544f9742ab08893dae0e86965a0
Closes-Bug: #1235080
Change Midonet vif driver to generic

Use generic vif driver for Midonet to support port bindings through
the mm-ctl script.

Change-Id: Iddc8a1c7b0128a76cd778c0245f2098bfb2c0145
Closes-Bug: 1235202
Split the creation of $STACK_USER account out of stack.sh

Automatically creating a new user account is not always the right course
of action when stack.sh is running as root.  Plus, the re-exec did not
work correctly in some cases.

* Create tools/create-stack-user.sh to set up a suitable user
  for running DevStack
* Abort stack.sh and unstack.sh if running as root and suggest creating a
  suitable user account.

Change-Id: I5d967c00c89f32e861449234ea8fe19261cd9ae3
Merge "Split the creation of $STACK_USER account out of stack.sh"
Merge "Fix typo in property passed to glance"
Merge "Change Midonet vif driver to generic"