Expose supported elements for running clusters

Registered by li,chen

Problem description
===================
We have build many elements into sahara image, and these elements number are going to grow. Some elements are supported by multiple plugins, while some only supported by one specific plugin.

For a certain cluster created by sahara, there is no way the user can know whether one element is supported or not unless he/she has enough knowledge on the plugin.

Blueprint information

Status:
Complete
Approver:
Sergey Lukjanov
Priority:
Undefined
Drafter:
None
Direction:
Needs approval
Assignee:
None
Definition:
Obsolete
Series goal:
None
Implementation:
Unknown
Milestone target:
None
Completed by
li,chen

Related branches

Sprints

Whiteboard

Gerrit topic: https://review.openstack.org/#q,topic:bp/add-config-for-elements,n,z

Addressed by: https://review.openstack.org/178892
    Add supported elements for clusters

Gerrit topic: https://review.openstack.org/#q,topic:bp/expose-elements,n,z

Addressed by: https://review.openstack.org/190959
    Create a description file for each image

Addressed by: https://review.openstack.org/193004
    Allow user to add the description file to sahara image

(?)

Work Items

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