App settings do not get removed after cleaning app/cache

### Actual behaviour
App settings do not removed.

### Expected behaviour
After cleaning app cache and settings, get fresh app.

### Steps to reproduce
1. Install
2. Some settings
3. Cleaning cache and data for nextcloud

### Environment data
Android version:
6.0.1

Device model:
Samsung Galaxy S6

Stock or customized system:
Stock

Nextcloud app version:
1.4.1 rc2

Nextcloud server version:
OC 9.1.2

### Logs
#### Web server error log
```
Insert your webserver log here
```

#### Nextcloud log (data/nextcloud.log)
```
Insert your Nextcloud log here
```