Added BodyListener format fallback in case no Content-Type is provided, defaults to %fos_rest.routing.loader.default_format%
Added fos_rest.body_listener.default_format parameter instead of relying on fos_rest.routing.loader.default_format
Fixed handling of fos_rest.body_listener.default_format config parameter.
Merge pull request #920 from gou1/body-listener-format-fallback

BodyListener default format in case no Content-Type is provided