One click publishing - step 2: add pepper support

[amir-zeldes]

Since GitDox can generate TTSGML, it should be possible to pipe generated SGML to Pepper and produce any supported format, e.g. generate an ANNIS corpus directly from GitDox. Ideally it should be possible to convert entire corpora via a Pepper job, selecting relevant documents using a top level corpus and/or status restriction (e.g. only convert documents from corpus X with status Y).