Fix an issue where the FormBodyWrapperFilter would encode the form parameters differently than on the original request.

The FormBodyWrapperFilter handles the application/x-www-form-urlencoded. In the case of requests received by curl or javascript, the FormHttpMessageConverter will reencode the parameters differently (for example, '(' will be encoded while it's not with the javascript encodeURIComponent method).

While this doesn't create any problem, the content length was not properly set in AbstractRibbonCommand. This causes the form params being stripped or the backend server would wait a long time for additional bytes depending on if the content length header was bigger/smaller than the actual data.