fix(errors): bring 404 and 405 errors into RFC compliance

Per RFC 7231 6.5 states that 4xx errors should include a message to the user.
Corrects the 404 and 405 errors so that developers may provide all the same options
as available with other errors (f.e description, title, etc) in order to make them
RFC compliance while preserving the same default behavior.

No breaking changes. Default behavior is same as legacy behavior.
Closes JIRA Issue #331.