networkmanager and new hidden SSID format (mac80211)

[dragoran <drago01 gmail com>]

When the old ieee based wlan stack are used hidden ssids are reported as 
<hidden> and network manager seems to work fine with them... but 
mac80211 no longer report them as hidden but as "" (empty string) and nm 
seems to show this for hidden ssids (which is wrong).
should be easy to fix..... (have not looked at the code yet)