Apply API Council comments to ConnectivityManager

rename isNetworkActive -> isDefaultNetworkActive
rename registerNetworkActiveListener -> registerDefaultNetworkActiveListener
make listenForNetwork/requestNetwork take a NetworkRequest
rename NetworkCallbackListener -> NetworkCallback
rename listenForNetwork -> registerNetworkCallback
rename releaseNetworkRequest -> unregisterNetworkCallback
remove NetworkRequest param from NetworkCallback functions
rename onNetworkCapabilitiesChagned to onCapabilitiesChanged
remove onReleased
change time units in onLosing from Sec -> ms

bug: 15142362
Change-Id: Ibc96e3f461706efe1eafa0d85605249cfd6e9fdd