Add two network related permissions to AndroidManifest.xml

XWalk Core library will auto detect network status, and below two permissions are needed:
  <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
  <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
Add these two permissions to AndroidManifest.xml

BUG=XWALK-1480