Bug 1010252 - Only forget connectingfail network triggered by user.

```javascript
  function updateNetworkState() {
    var networkStatus = gWifiManager.connection.status;
    var networkProp = gWifiManager.connection.network ?
        {ssid: gWifiManager.connection.network.ssid} : null;

    // networkStatus has one of the following values:
    // connecting, associated, connected, connectingfailed, disconnected.
    gNetworkList.display(gCurrentNetwork || gWifiManager.connection.network,
                         networkStatus);

    gWifiInfoBlock.textContent =
        _('fullStatus-' + networkStatus, networkProp);
```

Can we reuse `gWifiManager.connection.network` ? maybe something like `var network = gWifiManager.connection.network;` so that `networkProp` can reuse this value instead of querying it again.

And also, if we can't only use `gWifiManager.connection.network` based on previous comment, please comment the story there about why we need `gCurrentNetwork || gWifiManager.connection.network` here because this is a tricky story and nobody knows.