#89 symlink: Add non-ga base product type
Merged by lsedlar. Opened by lsedlar.
lsedlar/compose-utils symlink-base-product  into  master

The same layered product can be built for multiple versions of base product. We don't want colliding symlinks. For backwards compatibility the type is only added when it's not GA. This way it's also similar to how release IDs are generated in productmd.

Pull-Request has been merged by lsedlar