initial Best Network Selection implementation

-add dhcpserver, defaultGwMAC address, linked configuration and user choices link lists to WiFiconfiguration
-add default gateway mac address to RouteInfo
-add a Date to the ScanResult
-add BSSID date to the WifiConfiguration
- make framework auto-join into a config option
- add Settings option for showing RSSI in Wifi picker view; add auto-join specific status to WifiConfiguration

Change-Id: I5cfc4f2a48c9f3bc9766e8e68e24eff7b57f2821

 Changes to be committed:
	modified:   core/java/android/provider/Settings.java
	modified:   wifi/java/android/net/wifi/ScanResult.java
	modified:   wifi/java/android/net/wifi/WifiConfiguration.java