LP1955403-Bootstrap opac - Google Books preview not rendering.

LP1955403-Bootstrap opac - Google Books preview not rendering.

Fixes the Google Books preview in the Bootstrap Opac.

To test.
1. Set ctx.google_books_preview=1 in config.tt2.
2. View a bibliographic record that would have an ISBN that would link to
a google book preview.  In concerto you can change and ISBN on a record to
and ISBN that you know would pull data (9788027103782, 9781629795645).
3. Notice there is no preview button link, or preview.
4. Apply the patch and refresh.  The google preview button should render.
Clicking on the button will display the preview.

Signed-off-by: Garry Collum <gcollum@gmail.com>