manually create db-connection on test:purge.
Merge pull request #1101 from ontohub/fix_test_db_building

manually create db-connection on test:purge.
enforce hierarchy-sentences to end appropriately.
Merge pull request #1102 from ontohub/1100-fix_tree_generation

enforce hierarchy-sentences to end appropriately.
set the label as display_name for obo-symbols.
return the query-hash, not its last element.
save entity/symbol only if it is not null.
add migration to update display-name for obo

The symbols of obo-ontologies need an update.
This also pertains to the generation of
the class-hierarchy tree.
obey hound.
make hound obey - for migrations

Methods in Migrations are allowed to be longer.
use obo-label-names in sentences as well

This is solved by just calling set_display_text! on the
sentences at the right time (after the display_name for
the symbol has been updated).
add migration to update display_text of obo

Add the migration the update the display_text
of already existing obo sentences.
Merge branch '1099-label_symbols_in_obo_sentences' into develop