On 1.8.7 the Float class doesn't have the round(int) method. We were using this method on app/views/ratios/_bottom_js.html.erb, but it was replaced by some calculations, in order to support 1.8.7.
Please Monkey Patch Float if Ruby version == 1.8.7 and refactor app/views/ratios/_bottom_js.html.erb.
The plugin was completely redesign. Please try the new version.