Add a public accessor for a Request's ErrorListener.

Add a public accessor for a Request's ErrorListener.

Change-Id: Ifd3b8f818dd0e9db0183f08321043aae7c92c72c
Signed-off-by: Shirish Kalele <kalele@google.com>
Merge "Add a public accessor for a Request's ErrorListener."
Merge branch 'master' of https://android.googlesource.com/platform/frameworks/volley
update readme