Initial implementation of WifiScanner

This change implements basic functionality of WifiScanner. Following
functionality is enabled

1. Scanning - specify a list of channels to scan
2. Significant change detection
3. AP hotlist

Change-Id: Ieef75b96bdbbd3c7d9b9e698bd16e64d3b465254
diff --git a/Android.mk b/Android.mk
index beee726..99d73fa 100644
--- a/Android.mk
+++ b/Android.mk
@@ -320,6 +320,7 @@
 	wifi/java/android/net/wifi/IWifiManager.aidl \
 	wifi/java/android/net/wifi/hotspot/IWifiHotspotManager.aidl \
 	wifi/java/android/net/wifi/p2p/IWifiP2pManager.aidl \
+	wifi/java/android/net/wifi/IWifiScanner.aidl \
 	packages/services/PacProcessor/com/android/net/IProxyService.aidl \
 	packages/services/Proxy/com/android/net/IProxyCallback.aidl \
 	packages/services/Proxy/com/android/net/IProxyPortListener.aidl \