Propagate errors/warnings on API operations

[amarziali]

USER STORY

As a logisland API I would like to have the possibility to inform the caller about warnings or errors occurred while processing a request. In this case, we may always use a generic response envelope object containing a list of warnings and errors.

ACCEPTANCE CRITERIA

1. API is reviewed.

DEFINITION OF DONE

• Code builds without warnings (technical task)
• Code unit tested (technical task)
• Code is reviewed by a peer colleague
• Documentation updated (user story)
• Build pushed to demo server (user story)