require cover to approve, closing (#7) and (#21)

That's Renée's features 3 and 17.

BooksController:
    allow owner or admin to update book
    add approve, deactive, reactivate methods
    add approved to params

Books:
    add approve! and toggle_active! methods
    add not approved to approvable? method

Books index:
    column in admin view with links to approve, deactivate, reactivate book

Book show:
    remove extra line

config/routes.rb
    add approve, deactivate, reactivate routes to book members

spec/controllers/books_controller_spec.rb
    add approved to valid_attributes

spec/features/books_spec.rb b/spec/features/books_spec.rb
    only do one approved and one unapproved book per Index test
    it 'should not list the unapproved book titles'
    it 'should list the approved book titles'
    describe 'As Admin'
      it 'should list the unapproved book titles'
      it 'should let us approve unapproved titles'
      it 'should let us deactivate approved titles'
      it 'should let us reactivate deactivated titles'

100% simplecov, all tests passing
flay: 1573
flog: 2721.6 / 10.3