Added at_least_one_of parameter validator.
Set status for Endpoints when an error occours like #697
Merge pull request #698 from dspaeth-faber/set_endpoint_status_for_errors

Set status for endpoints when an error occours
added a spec and documentation for default status codes
Merge pull request #701 from dspaeth-faber/document_status

added a spec and documentation for default status codes
Merge pull request #692 from dblock/at-least-one-of

Added at_least_one_of parameter validator.