code: merge request

change signature constructObservableValue

allow cancel Job

address merge reguest notes:
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5610
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5615
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5580
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5582
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5583
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5584
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5585
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5599
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5623
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5644
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5652
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5653
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5655
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5659
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5673
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5674
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5676
https://code.it4i.cz/fiji/haas-java-client/merge_requests/15#note_5675