BK-2393 Remove deprecated button and import template

[danielhjames]

Because the Create New Book dialogue now handles imports much better.

Also, uncommenting the 'Show in a list' option which we now have space for again, because users with lots of books on their Dashboard were missing that feature.

[ride90]

Hi @danielhjames ,
This PR will throw error if you visit page "/accounts/username/".
Booktype/lib/booktype/apps/account/templates/account/dashboard.html includes account/dashboard_import_book_modal.html inside (line 210).
Please, fix it and update pr.

[danielhjames]

Thanks for catching that @ride90 , I did not experience this on the airr site as I had left the old template in place. Template has been updated in a new commit.