Build fedora-28 DIBs with nodepool-builder

Fedora-28 is the next release of Fedora. While not officially released
yet, beta images have been confirmed to work using nodepool dsvm job.
Bring the images online first, before we configure jobs to use them.

Change-Id: If66f1cffb46847cc256bcc242332ceda41bc8482
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

nodepool/nodepool.yaml

@@ -43,6 +43,8 @@ providers:
         config-drive: true
       - name: fedora-27
         config-drive: true
+      - name: fedora-28
+        config-drive: true
       - name: gentoo-17-0-systemd
         config-drive: true
       - name: opensuse-423
@@ -164,6 +166,27 @@ diskimages:
       DIB_GRUB_TIMEOUT: '0'
       GIT_HTTP_LOW_SPEED_TIME: '300'
       GIT_HTTP_LOW_SPEED_LIMIT: '1000'
+  - name: fedora-28
+    pause: false
+    elements:
+      - fedora-minimal
+      - vm
+      - simple-init
+      - openstack-repos
+      - nodepool-base
+      - cache-devstack
+      - initialize-urandom
+      - growroot
+      - infra-package-needs
+    release: 28
+    env-vars:
+      TMPDIR: /opt/dib_tmp
+      DIB_CHECKSUM: '1'
+      DIB_IMAGE_CACHE: /opt/dib_cache
+      QEMU_IMG_OPTIONS: compat=0.10
+      DIB_GRUB_TIMEOUT: '0'
+      GIT_HTTP_LOW_SPEED_TIME: '300'
+      GIT_HTTP_LOW_SPEED_LIMIT: '1000'
   - name: gentoo-17-0-systemd
     pause: true
     elements: