Fixed a funny bug on request of ontologies by their short URL.
Refactored Hets class to use the Subprocess helper.

This allows better error handling.
Better repository index and some refactoring.
Display "Ontologies" headline only if not showing a certain ontology.
Merge branch 'develop' of github.com:ontohub/ontohub into develop
Error messages formatted.
Seeds fixed
Merge branch 'augmenting181_catalog_mechanism_for_repositories' into develop
pass url catalog to hets
add hets test for url catalog
solve merge conflicts
Merge branch 'develop' into augmenting181_catalog_mechanism_for_repositories