Test if _format requirement is not already set before overwriting it
adding tests for PR#476
passing formats to the RestRouteLoaded in tests allows _format to be set
Fixing _format requirements made available to developers - comments
_format requirement - removed a useless comment part
_format default behavior documented with the possibility to override it
Fix doc for _format overriding
Merge pull request #476 from zefrog/allow-custom-format-requirements

Test if _format requirement is not already set before overwriting it