The Add folder modal does not disable the add button while loading

1. Get on a TGV.
2. Log onto the onboard Wi-Fi.
3. Accidentally cause the Wi-Fi portal to crash, while still having Internet access.
4. Under the Actions menu, click on Add folder.
5. Type in a folder name and type.
6. Click the Add folder button over and over.
7. Get lots of notifications for many created folders.
8. Admire the many duplicate folders that are now in the list.
9. Cry.

The modal should mark the button as disabled, add a is-loading class, and prevent creating with a if (!this.loading) when the button is clicked.