container: add global vars for image-build tasks

composes were failing because the 2nd image build task
for the minimal image (copied from fedora.conf) didn't
have some variables defined. In fedora.conf the global_*
vars are defined, so let's do that here too.

Signed-off-by: Dusty Mabe <dusty@dustymabe.com>

fedora-docker.conf

@@ -201,17 +201,19 @@ disc_types = {
 translate_paths = [
    ('/mnt/koji/compose/', 'http://kojipkgs.fedoraproject.org/compose/'),
 ]
+
+# These will be inherited by live_media, live_images and image_build
+global_ksurl = 'git+https://pagure.io/fedora-kickstarts.git?#origin/f26'
+global_release = '!RELEASE_FROM_LABEL_DATE_TYPE_RESPIN'
+global_version = '26'
+global_target = 'f26'
+
 image_build = {
     '^Docker$': [
         {
             'image-build': {
                     'format': [('docker', 'tar.xz')],
                     'name': 'Fedora-Docker-Base',
-                    'target': 'f26',
-                    'version': '26',
-                    'release': None,
-                    # correct SHA1 hash will be put into the URL below automatically
-                    'ksurl': 'git+https://pagure.io/fedora-kickstarts.git?#origin/f26',
                     'kickstart': 'fedora-docker-base.ks',
                     'distro': 'Fedora-22',
                     'disk_size': 5,