Open Library search API

If nothing is found on the server, returns results from open library
API. Clicking on a book imports it.

internal/apitest/get_book_test.go

@@ -15,6 +15,7 @@ type fetchedBook struct {
 	Title         string `json:"title" binding:"required,max=300"`
 	Author        string `json:"author" binding:"max=100"`
 	ISBN          string `json:"isbn"`
+	OpenLibraryId string `json:"openlibraryid"`
 	Summary       string `json:"summary"`
 	Rating        int    `json:"rating"`
 	Read          bool   `json:"read"`