Cross-compilation + Correct publishing support

You need to add the jsuereth plugin in your user plugins to sign artifacts before publishing, that's the good practice.

I'v changed organization to be able to publish on maven under my name, and use it in my sbt 0.11.3 based projects, you should of course ommit this commit.

I don't know what's point of scripted plugin, but I wasn't able to get it for 0.11.3 so I removed it ... and it look like the plugin still work like a charm.