Add Nord color theme (#110)

* Color scheme courtesy of folks at arcticicestudio:
  https://arcticicestudio.github.io/nord/

src/app/accounts/settings.component.ts

@@ -64,6 +64,7 @@ export class SettingsComponent implements OnInit {
             { name: i18nService.t('default'), value: null },
             { name: i18nService.t('light'), value: 'light' },
             { name: i18nService.t('dark'), value: 'dark' },
+            { name: 'Nord', value: 'nord' },
         ];
     }