Embed browse plugin

Fixes #29 

Adds embedded browse functionality to an "At the library" show page. JS plugin overwrites the link locations so that non JS browsers will still click through to a link to the browse page.

![screen shot 2014-06-24 at 5 24 36 pm](https://cloud.githubusercontent.com/assets/1656824/3380144/72747400-fbff-11e3-8c9e-59292ef968ef.png)

![screen shot 2014-06-24 at 5 25 01 pm](https://cloud.githubusercontent.com/assets/1656824/3380147/77f0b088-fbff-11e3-8d58-00ee96353829.png)

Left and right browse more boxes with links to the original item browse page.

![screen shot 2014-06-24 at 5 25 08 pm](https://cloud.githubusercontent.com/assets/1656824/3380152/9feeff9a-fbff-11e3-8952-f591d5a881c6.png)

![screen shot 2014-06-24 at 5 25 14 pm](https://cloud.githubusercontent.com/assets/1656824/3380154/a3be71be-fbff-11e3-992f-a8961227b30f.png)


Not really that important, but I wonder if we should have that icon point the other direction when being viewed in the far left threshold.

![left-threshold](https://cloud.githubusercontent.com/assets/96776/3405521/71242ea8-fd7e-11e3-90e3-8bc63e7a1999.png)