Added import job which executes a shell script and loads the created dump

As we worked with the pipeline we run into the situation where we had to import dumps which did not comply with any standard (e.g. IMDb). In order to process these dumps with ldif we needed more flexibility.

Therefore we added this ImportJob which allows us to import arbritrary things into the pipeline. It is simply an ImportJob class which executes a shell script and reads in a triple afterwards. This is just a proposal as it opens the pipeline to any kind of extension.