Use $() instead of ``

There are other instances of this in other files, just tidying
ceilometer at the moment.

Change-Id: I136a20d7ac50fdf02cbd1102613e324e313b7b0a
Merge "XenAPI: Always update apt sources"
Merge "Use $() instead of ``"
XenAPI: move Neutron plugin install to domU

Use the same mechanism as used for nova plugin installation, thus
avoiding the need for variables in dom0. This change will also help to
move XenServer CI to neutron in the future, as the dom0 part of the
script is not executed there.

With this change, the neutron related network will always be created and
attached even if the user wants to use nova-network.

Change-Id: I8669c94e9f0aacce2990469dbabde1ff702a2769
XenAPI: Remove non-used functions

Remove the no-longer used functions that were used to download plugins
to dom0.

Change-Id: I8dfd476781b683a8378efdae45d3cb1b46e7063c
XenAPI: workaround for unsupp. associative arrays

Dom0's bash does not support associative arrays, however we source
`functions` and therefore our scripts fail. This change breaks the
dependency od dom0 tools on domU functions.

Fixes bug: 1379804

Change-Id: I229e2d5f07070a9236ec612d4032c94c4361a9f6
XenAPI: Always update proxy settings

If a user wants to re-use an xva just with different proxy settings, he
can now do it, as this change will always update /etc/apt/apt.conf to
reflect the settings in the user's localrc.

Change-Id: I8a6e9c88304bc887ea8269d946e89a5ba258b126
Merge commit 'refs/changes/11/129211/1' of git://gold.eng.hq.xensource.com/git/github/openstack-dev/devstack into tmpbranch