bibconvert: update arxiv-to-inspire-categories.kb

* Adds translation of categories within arXiv-repositories to
  INSPIRE categories.

* E.g. astro-ph.CO to Astrophysics.

Signed-off-by: fschwenn <florian.schwennsen@desy.de>
Merge pull request #54 from fschwenn/arxiv-to-inspire-categories

bibconvert: update arxiv-to-inspire-categories.kb