[data processing] Need to mark cluster template field as required

[Chad Roberts]

Priority *wishlist*.

This change was made to the sahara-dashboard repo after the merge process began. It needs to be merged into the new horizon codebase.

Original patch: https://review.openstack.org/#/c/101927/

Steps To Reproduce:
1. Install OpenStack with Sahara.
2. Login to Horizon dashboard.
3. Upload Sahara image (Ubuntu).
4. Navigate to Sahara > Image Registry and register new image for Sahara clusters.
5. Navigate to Sahara > Clusters.
6. Click Launch Cluster, click Create.
7. Set Name of cluster, select image for cluster and Neutron network (all required fields) - and do not select anything for Cluster Template field (let's use default 'empty' value).
8. Click Create

Expected Result:
When user set values for all required fields in Horizon, cluster should be created successfully.

Observed Result:
Error message 'Cluster hasn't attribute "node_groups"' and user can't create cluster, if he don't knows how Sahara works. Of course, all will work fine if he will register template and templates group before the cluster creation.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/103976

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/103976
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=4b4fd31b1aefa74e8229b3a92b5d01691575f0c3
Submitter: Jenkins
Branch: master

commit 4b4fd31b1aefa74e8229b3a92b5d01691575f0c3
Author: Chad Roberts <email address hidden>
Date: Tue Jul 1 15:17:06 2014 -0400

    Data Processing: Making cluster template field required

    The cluster_template field is now required in order to
    create a cluster. The user will now be prompted to choose
    a cluster template if they forget to pick one.

    Change-Id: If10029164aa69702da3c5255a29fdd6ddaaa3b8d
    Closes-Bug: bug #1336300
    Co-Authored-By: Timur Nurlygayanov <email address hidden>