Need to use asset_path for Jcrop.gif

[jfly]

Right now, Jcrop.gif doesn't get compiled as part of the asset pipeline. I use nginx to serve up static resources, so the request for Jcrop.gif doesn't succeed. The css file should be an erb file that calls asset_path.

I can submit a PR for this if desired.

[aspirewit]

We can also put the Jcrop.gif into the folder vendor/assets/images

Finaly, overriding the stylesheet in the scss file:

.jcrop-vline,
.jcrop-hline {
  background: #ffffff url(asset-path("Jcrop.gif")) !important;
}