Adds basic vuejs functionnality, implements RecipeCategory custom field

cookbook/src/bin/show_recipes.rs

@@ -15,7 +15,7 @@ fn main() {
 
     println!("Here are {} recipes :", result.len());
     for rec in result {
-        println!("*************\n{}", rec.title);
+        println!("*************\n{}\n({:?})", rec.title, rec.category);
         println!("-------------\n");
         println!("{}", rec.ingredients);
     }