Address API Council feedback for WifiAdapter/WPS APIs

This change addresses concerns from the API review. Things that
are fixed are -

1. WifiAdapter is removed, until we have 'real' support for it
2. All the methods from WifiAdapter are moved to WifiManager
3. Changed WPSListener API names to be onFailed/onSucceeded et al
4. Removed ActionListener from WPS APIs, they now take WpsListener

Bug: 16403303
Bug: 17115004
Change-Id: I609c42f08b52f77240ce9a97b1a9941a9c154752