admin: Remove unnecessary function in actions
admin: Add details url

Also, fix typo (diplay_name --> display_name).
admin: Add item_name in extra JSON
admin-ui: Minor html modifications
admin-ui: Adjust the functionality of the table to new json form
Merge branch 'feature-admin-ui' into feature-admin
admin-ui: Refactor the selection/deselection functionality

Also, the way the actions get enabled or disabled is modified.
admin-ui: Update buttons and modals
admin-ui: Overall refactor of javascript code

Also, the files extra.js and tables.js are merged in the former.
admin-ui: Style modifications
Merge branch 'feature-admin-ui' into feature-admin