Add handling of parameter replacements.

We will need to replace the use of Parameters in the included template
with actual values in many cases.

Change-Id: I95fc9116dc2bba74c31d5570851c5c4eb476291a
Add an example of Type: FileInclude.

Change-Id: Ie9d45ea5e26e38e8782e7a3d0a626e36090f5388
Generate overcloud.yaml using overcloud-source.

This new version does not need any nested stacks and correctly
references notcompute.

Change-Id: I16f846f7983a956b5159d17bef85cf6a87d69b45