Update the _examples/mvc/login example - add a Path property at mvc.Response and add a context.Proceed helper function

Former-commit-id: b898901fe4a324e888a6e09c93530cf7a551cf2a

_examples/mvc/login/web/middleware/basicauth.go

@@ -0,0 +1,12 @@
+// file: middleware/basicauth.go
+
+package middleware
+
+import "github.com/kataras/iris/middleware/basicauth"
+
+// BasicAuth middleware sample.
+var BasicAuth = basicauth.New(basicauth.Config{
+	Users: map[string]string{
+		"admin": "password",
+	},
+})