add login to quasar backend

backend/models/user.go

@@ -0,0 +1,11 @@
+package models
+
+type User struct {
+	Name     string `json:"user"`
+	Password string `json:"password,omitempty"`
+	Token    string `json:"token,omitempty"`
+}
+
+func (u *User) IsValid() bool {
+	return u.Name != ""
+}