@method parse
Parses the a buffer into the expected internal type, based
on standard request headers (content-type and charset).

@param  {buffer} buff The initial buffer value to parse.
@param  {object} headers Used to select the conversion strategy.
@return {object} Parsed post-body according to content-type and charset.
function parse(buffer, headers) {
    var params = getParsingParams(headers);
    var strategy = PARSING_STRATEGIES[params.contentType] ||
            function (/*buffer, headers*/) { return null; };

    try {
        return strategy(buffer, params.charset);
    } catch (err) {
        // Might be nice to do some logging here.
        return null;
    }
}