This adds a script that can be used to create a new site definitions
based on reference manifests in treasuremap. It does the following:
1. clone treasuremap at the appropriate tag/branch
2. create a project side-by-side with airshipctl/treasuremap
3. copy in reference site manifests
4. update the site's metadata.yaml appropriately
5. create & update an airship config file for the site
Change-Id: Ied0403cc9df461a1a1ee75fca0caf17fb56055bc
9f51669d61