Add HTML POST Form support in Bind

gin.go

@@ -23,6 +23,7 @@ const (
 	MIMEXML      = "application/xml"
 	MIMEXML2     = "text/xml"
 	MIMEPlain    = "text/plain"
+	MIMEPOSTForm = "application/x-www-form-urlencoded"
 )
 
 const (
@@ -407,7 +408,7 @@ func (c *Context) Bind(obj interface{}) bool {
 	var b binding.Binding
 	ctype := filterFlags(c.Req.Header.Get("Content-Type"))
 	switch {
-	case c.Req.Method == "GET":
+	case c.Req.Method == "GET" || ctype == MIMEPOSTForm:
 		b = binding.Form
 	case ctype == MIMEJSON:
 		b = binding.JSON