installer images created via libvirt or container

When using rpm-os-toolbox to create installer images (PXE and isos),
lorax and friends really want to run in the native operating system. So,
for example, creating a centos installer image on a Fedora system will
fail.  We now by default use a container to create the image.  You can also
pass --virt to use imagefactory and indirection.

* installer.py
    - createContainer() does the work for the container bits
    - createContainer requires docker_os_name which defines the container
      base OS.  Like fedora:rawhide or centos:latest
    - create uses indirection
    - subjected entire file to pep8 and flake corrections

* imagefactory.py
    - small changes to allow installer.py to reuse some of its classes

* taskbase.py
    - added docker_os_name to ATTRS
    - added parsing of util_uuid which allows to re-use and existing
      imagefactory utility image to cut down on processing time

* lorax-http-repo.tmpl
    - New file for using ostree httpd sync'ing

* lorax-indirection-repo.tmpl
    - New file for using imagefactory indirection to build installer images

* Makefile-toolbox.am
    - added installation of the lorax-http-repo.tmpl
    - added installation of the lorax-indirection-repo.tmpl

* rpm-ostree-toolbox.spec.in
    - Add requires for docker and IndirectionCloud