Base for rest api utilisation

The restConsumer will be the base, then I will create a js file per
"object" (for instance there will be users.js with all endpoints for
users using the restConsumer.js)

frontend/src/utils.js

@@ -0,0 +1,17 @@
+/**
+ * Return the content of a cookie with specified key
+ * @param key cookie name
+ */
+function getCookie(key){
+	key = key + "="
+	let cookies = decodeURIComponent(document.cookie).split(";");
+	for (let el of cookies) {
+		el = el.trimStart();
+		if(el.indexOf(key) == 0){
+			return el.substr(key.length, el.length);
+		}
+	}
+	return "";
+}
+
+export {getCookie};