Function cargo::call_main_without_stdin

pub fn call_main_without_stdin<T, V>(exec: fn(T, &Config) -> CliResult<Option<V>>,
                                     config: &Config,
                                     usage: &str,
                                     args: &[String],
                                     options_first: bool)
                                     -> CliResult<Option<V>> where V: Encodable, T: Decodable