Settings: Handle download complete in background thread.

Change-Id: I448826fed123b95a23bd5b303a639ddc872d7fb2
Settings: Reset state when shutdown

Change-Id: Iec82e7086a5d807e9fcc7dca5278be64fe0d5890
Settings: Switch all network requests to utilize Volley.

Change-Id: I1decc74c5575527c71833abfbfd79225dcb79123