Remove unused settings

the img_* related variables are unused in the
templates, remove them.
Fix admin credentials

Use KeystoneHelper Settings everywhere. Fix admin
tenant.
Tempest assumes that the alt-flavor has more ram

So resort the flavors we create. Adjust RAM settings.
Remove disk allocation as that just fills up on mkcloud
installs.
Fix cleanup of neutron routers

Neutron routers need to have their interfaces
removed before they can be deleted (this is
independent from the port list apparently)
Enable Nova resize tests
Enable Horizon dashboard testing
Set flavor for Heat tests

This flavor type is likely too small, but at
least doesn't abort right at the start.
Add admin as admin to tempest tenant

Heat tests require the admin user to have
admin privileges in the tempest tenant.
Enable Ceilometer tests
Enable testing of FWaaS extension

This is unconditionally enabled now for Icehouse
and newer, so test it.
Upload cirros images as public

For the cross_tenant_traffic test, the img flavor needs
to be available in tenant, and alt_img in alt_tenant.
Since we however use img and alt_img from the same image,
the image needs to be made public so that it can be
accessed from both tenants. Alternative would be to
upload the image twice, once for each tenant and set
the img ids correspondingly.
Adjust smoketest run