web/multinode: Show appropriate error while adding new node

While adding new nodes, if the nodeID, Public IP Address or
the API Key are incorrect no error was being shown on the webpage.
This commit resolves this issue by showing a error notification on
the top right corner of the screen with appropriate error text.

web/multinode/.eslintrc.js

@@ -43,7 +43,7 @@ module.exports = {
         "vue/no-unused-refs": ["warn"],
         "vue/no-useless-v-bind": ["warn"],
 
-        'vue/no-unregistered-components': ['warn', { ignorePatterns: ['router-link', 'router-view'] }],
+        'vue/no-unregistered-components': ['warn', { ignorePatterns: ['router-link', 'router-view', 'notifications'] }],
 
         'storj/vue/require-annotation': 'warn',
     },