change dateCreated to a string (from a Date object, which persists as a Date object)

src/views/ImportAccountView.vue

@@ -79,7 +79,7 @@ export default class ImportAccountView extends Vue {
         const num_accounts = await db.accounts.count();
         if (num_accounts === 0) {
           await db.accounts.add({
-            dateCreated: new Date(),
+            dateCreated: new Date().toISOString(),
             derivationPath: this.derivationPath,
             identity: JSON.stringify(newId),
             mnemonic: mne,