Check box drama - [Delivers #81868156]

Books have 'selected' attribute, which can be changed via checkboxes or 'clear selected books' link (json and js methods, respectively). User can see all selected books via 'view selected books' link. Someday, from this view, they will be able to print labels or a list of the selected books. Right now they can just look at them in wonder. 

There are controller tests, but no capybara tests because I couldn't get them to work. View https://github.com/cherimarie/LibraryCollection/tree/testing_checkbox_drama_omg for more details on that adventure.