Trim whitespace and allow API key to be removed

src/lib/Home.svelte

@@ -26,7 +26,9 @@ $: apiKey = $apiKeyStorage
         class="field has-addons has-addons-right"
         on:submit|preventDefault={(event) => {
           if (event.target && event.target[0].value) {
-          apiKeyStorage.set(event.target[0].value)
+            apiKeyStorage.set((event.target[0].value).trim())
+          } else {
+            apiKeyStorage.set('') // remove api key
           }
         }}
       >