xenapi: cleanup VM Installation

VM installation created a machine with multiple network interfaces. This
is a needless complexity at that point, we only need one interface. This
change removes the complex network interface setup from
install-os-vpx.sh script, so that only one network interface is created,
which is connected to the selected network (management by default). This
change also removes a lot of non-used code from install-os-vpx.sh
Specify the network to be used for ubuntu netinstall with:

    UBUNTU_INST_BRIDGE_OR_NET_NAME

defaults to $MGT_BRIDGE_OR_NET_NAME.

This change also includes:
 - use precise as default

Related to blueprint xenapi-devstack-cleanup

Change-Id: Ib0a0a316e849f2c2651305ea657c84820cd2bb3b
Set the scenario/img_dir option for tempest.conf

The default value does not work unless devstack is installed in
/opt/stack/new/devstack. This patch changes the img_dir option to point
to the correct install location.

Change-Id: Iea41d209dad10b2f9a7c97efd55c39a8d29347cc
Directly install requirements with pip

Rather than parsing then feeding the pip requirements file to pip,
just have pip consume it directly.

Change-Id: I17bbe4324e6957c7165bc0f340ddae1e51039471
Rename quantum repos to neutron

Only the repos are renamed.  This will coincide with the repo rename
operation on July 6.

See https://wiki.openstack.org/wiki/Network/neutron-renaming

Change-Id: I99fe1f80ffc7a54b958b709495b90f8d94d41376
update for name change to Neutron

Note: Nova and Horizon are not updated until those projects have
migrated.

Change-Id: I256ef20e7caadd9c96e6dd908c5d8b69ca5c4aeb
Merge "Directly install requirements with pip"
Merge "update for name change to Neutron"
Merge "Set the scenario/img_dir option for tempest.conf"
Merge "xenapi: cleanup VM Installation"
Start using cinder rest api v2 by default

It's ready, it's time. Has deprecation support for v1 parameters as
well.
default to v2 in openrc

Change-Id: Ia93707a6f40f5eea0d3e6d70e673e301017e1114