Add python tuskar client

Add python tuskar client
Heat version to latest stable-juno

We need latest stable-juno version of heat, which has for example
fixed stack-update.
Also adding a note about variable needed to be set, so this
reporefs are actually used.
Calling Tuskar CLI properly

As tuskar CLI is added properly here
https://review.openstack.org/#/c/130714/ ,
we can call it properly in instack now.

This was also breaking the packaged install. Fixing also
path for Tuskar templates, which also breaks the packaged
install.
Store keystone certificates to Tuskar

At first cleaning the ugly sed of the json file. But also stores
these certificates to tuskar. As tuskar should hold all the
parameters. Otherwise it would not be fully compatible with UI.
Freeze templates version because of Tuskar

We need templates that are supported by Tuskar, before Tuskar
will know how to work with the new ones.
Install tuskar client as package by default

Install tuskar client as package by default
Merge pull request #83 from Divius/master

More workarounds in discovery ramdisk
Merge pull request #78 from Ladas/master

Heat version to latest stable-juno
Blacklist 00-rhel-registration

The registration process has to be completed before instack is run,
so we don't need to run this script and it breaks if we try to.
Blacklist registration on source installs too

This will almost certainly be necessary too.
Update README-packages.md

Added additional url for rhel to make it more obvious
Add isolated-build element

To be used for Koji/Brew builds.
Add missing backslash

Add missing backslash to stack-update
Merge pull request #84 from Ladas/master

Add missing backslash
Update README-packages.md
Update README-packages.md
Update README-packages.md
Update with new url of stage repo
Download the fedora cloud image if necessary.

On a completely clean system where you've only built rhel7 images the fedora
cloud image doesn't exist in the cache, so we must download it manually.
Add rhos-release element and use it in instack-build-images when building RHOS images