Added a function to grab the site-packages directory from a virtualenv
Support creating disk volume via libvirt

Tested on VMware ESXi.

Note that a new configuration directive is introduced with this patch:

.. code-block:: yaml

    libvirt:
      storagepool: poolname
Merge branch 'develop' into libvirt-define-vol
Merge pull request #6858 from s0undt3ch/features/states-reload

Allow salt modules to be refreshed on demand.
Merge pull request #6860 from whiteinge/get_site_packages

Added a function to grab the site-packages directory from a virtualenv
Add virt.stop alias for virt.destroy

Analogous to virt.start vs virt.create.
Merge pull request #6863 from holmboe/libvirt-define-vol

Libvirt define vol
Merge pull request #6864 from holmboe/virt-stop

Add virt.stop alias for virt.destroy
Also reload python's `site` module which handles `site-packages`.

In case a package has been installed into the current python process 'site-packages', the 'site' module needs to be reloaded in order for the newly installed package to be importable.