Error results can now maintain a map of headers.

The Method Fail states now use this to set Allow headers.
Allow the servlet result handler to set headers on an error message.
Ensure that there is a space between commas in Allow header.
Added method fail step tests to make sure allow header is set.
Added header assertions to validator tests where we expect a 405.
Merge pull request #140 from InABlender/allow

Add Allow header or 405 error