Improvments

First of all, thanks for the great Book Review plugin. This saved me a lot of time to develop on my own.

Now, when I wanted to configure the plugin for a client I noticed a few small things that I wanted to place as suggestions to improve:

1. In book-review-public.php it would be good if the top div has a class attribute book-review instead of a id attribute book-review: <div class="book-review" ...
   Semantically id here is not correct because I potentially can have multiple divs with the same id on my page.
2. In class-book-review-public.php it would be good to only add $style = 'border-style: solid;'; if $border_width is actually set or greater then 0. My problem here is that I cannot remove the border. If border-style is added conditionally, I can choose not to render the border.
3. I sometimes paste ISBN numbers from online resources which include dashes (-). Would be nice to do a simple str_replace to remove all dashes from the input string before calling the API. This would save me the little work of removing them every time before I submit the request.

Feel free to contact me if you have any questions on my suggestions.

Thanks!