Add translator for beck-online (journals only)

* beck-online is a German law aggregator, see http://rzblx10.uni-regensburg.de/dbinfo/detail.php?bib_id=alle&colors=&ocolors=&lett=fs&tid=0&titel_id=1168
* journals contain articles, cases and other stuff
* translator works for journals but NOT for handbooks, regulation textes, legal commentaries
Merge pull request #707 from zuphilip/master

Add translator for beck-online (journals only)