This patch updates the variants DTD and parsing to allow specifying
multiple build install packages for each variant.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
CHANGE: Rename product_* config options to release_* for consistency with productmd.
ACTION: Rename product_name, product_short, product_version, product_is_layered to release_* in config files.
Rename //variant/product to //variant/release in variants XML.