Draft material has default cover image

[hans]

Draft material has always default cover image. This will improve the difference between draft and published material. We can also get rid of those ugly and non-intuitive embedded icons.

This means the following changes:

• For draft material link “Publish” is displayed under the default cover image instead of “Change cover image”.
• “Publish” link leads user to “Publish Material” page that has following elements: short text explaining the difference between draft and publish status, “Upload cover image“ field, buttons “Publish” and “Cancel”.

Vocabulary:

• "Publish a Learning Resource"
• "Initially all the learning resources in LeMill are in draft status. Draft resources have a default cover image and its authors are not shown. You can publish the learning resource any time when you consider it to be ready. To publish a resource you have to upload cover image or search for a suitable image from media pieces."
• "Publish"
• "Cancel"

[tarmo]

Vocabulary changes done, functionality not.