Need to reload WebDAV preferences page to get password input box to appear

I'm using authfronted.cas so Pydio doesn't know user password and need to ask for it after enabling WebDAV, but I found that this doesn't happen and I need to reload WebDAV preferences page to get a password input box.

To be sure that it wasn't a misconfiguration, I also set this configuration options:
```
WEBDAV_FORCE_BASIC = false
SESSION_SET_CREDENTIALS = false
TRANSMIT_CLEAR_PASS = false
```

After that, I found what I think that is wrong, the expression that checks if password form has to be shown after enabling WebDAV:

```javascript
if(!ajaxplorer.webdavCurrentPreferences.digest_set
    && ajaxplorer.webdavCurrentPreferences.webdav_force_basic)
```

It's cheking if WEBDAV_FORCE_BASIC is enabled when it should be just the opposite, shouldn't it? I mean, password form should be shown when WEBDAV_FORCE_BASIC is false and thus Digest auth is going to be used.

This is why it works after reloading the page. There, the condition is right:

```javascript
if(activator.checked && !ajaxplorer.webdavCurrentPreferences.digest_set
    && !ajaxplorer.webdavCurrentPreferences.webdav_force_basic)
```