func setup(c *casket.Controller) error {
	config, err := mimeParse(c)
	if err != nil {
		return err
	}
	httpserver.GetConfig(c).AddMiddleware(func(next httpserver.Handler) httpserver.Handler {
		return Mime{Next: next, Configs: config}
	})
	return nil
}
setup configures a new mime middleware instance.
package mime
import (
	"fmt"
	"strings"
	"github.com/tmpim/casket"
	"github.com/tmpim/casket/caskethttp/httpserver"
)
func init() {
	casket.RegisterPlugin("mime", casket.Plugin{
		ServerType: "http",
		Action:     setup,
	})
}