Add im4java and move config out of URL space

1/ We can have a bake-off between im4java and scalr.

2/ I've moved width, height etc. out of the URLs for two reasons.

Firstly, it's trivial to DOS a site with image dimensions in it's parameters,

```
[5000..10000].each { |width| `curl http://path/to/image/#{width}/#{height}/jpg` }
```

Secondly, we favour [permanent URLs](http://www.w3.org/Provider/Style/URI.html). Adding the dimensions and compression ratio to your URLs guarantees
you'll change them frequently, screwing up your caches and worsening your SEO.