Integrate users and books

- new table userbook linking users and book
- moved rating to users book
- updated demo data and tests
- updated front to hide routes from non connected users

front/src/api.js

@@ -24,8 +24,8 @@ function useFetch(url) {
   return { data, error }
 }
 
-export function getBooks() {
-  return useFetch(baseUrl + '/books');
+export function getMyBooks() {
+  return useFetch(baseUrl + '/mybooks');
 }
 
 export function postBook(book) {