Implement CreateHIT response parsing, refactor SearchHITs parsing

Signed-off-by: Thomas Steffes <tsteffes@roomkey.com>
Further refactoring of HIT response parsing

Signed-off-by: Thomas Steffes <tsteffes@roomkey.com>
Implement RejectAssignment operation

Signed-off-by: Thomas Steffes <tsteffes@roomkey.com>