[telemetry] Retry Cloud Storage download on 500 error.

[telemetry] Retry Cloud Storage download on 500 error.

Also remove logic for 401 errors. I don't think this is the correct thing to do, and covers up the real failure.

BUG=418225
TEST=None.
R=tonyg

Committed: https://crrev.com/d42f51125238a34b4d16841207105967c69228c0
Cr-Commit-Position: refs/heads/master@{#297103}

[tonyg, 2014-09-26 22:06:10]

lgtm

[dtu, 2014-09-26 23:05:20]

The CQ bit was checked by dtu@chromium.org

[commit-bot: I haz the power, 2014-09-26 23:06:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/608933002/1

[commit-bot: I haz the power, 2014-09-27 04:23:13]

Committed patchset #1 (id:1) as cb7591329a351183532b222eac74632f09dcc651

[commit-bot: I haz the power, 2014-09-27 04:24:01]

Patchset 1 (id:??) landed as
https://crrev.com/d42f51125238a34b4d16841207105967c69228c0
Cr-Commit-Position: refs/heads/master@{#297103}