Add group wishlists

[Encotric]

As a group owner, I want to be able to see a wishlist of items, which users request. The items should be visible to all group members, but only editable by the creator and group owner. Moreover, it should be possible to edit all known item attributes (based on the item category)

Dependencies

Depends on:

• Add user membership management to group management #106
• Add group details page #233

Acceptance Criteria

• a group owner can see an item wishlist on the group management page
• a group owner can edit items on the wishlist to extend their attributes or remove them when inappropriate or fulfilled
• a group member can add new items to the wishlist on the group details page of a group
• a group member can see all items currently on the item wishlist on the group detail page of a group
• a group member can edit his own items added to the wishlist to extend its attributes