Chore: 1.4.0

# [1.4.0](https://git.rwth-aachen.de/coscine/ts/app-util/compare/v1.3.2...v1.4.0) (2020-06-19)

### New

* Included Functionality for Slugs (coscine/issues#804) ([690c4968](https://git.rwth-aachen.de/coscine/ts/app-util/commit/690c49680dd155d0cd71276c58ad1ca77d9f2173)), closes [coscine/issues#804](https://git.rwth-aachen.de/coscine/issues/issues/804)