Add owned field for book

[royto]

Could be interresting to have this new field to track if a book is owned or not

[Mozzo1000]

Hi @royto
Thank you for opening up this issue. I am thinking this feature would sit nicely together with #56 Add book shelf information. As you might own a book and then want to place it in a location such as a bookshelf.

I am not really sure how this would present on the frontend so I will have to think about that some more.