Roll tools/swarming_client/ to c8437bfa40aa3428ee7655585b6203f2cac67693.

Roll tools/swarming_client/ to c8437bfa40aa3428ee7655585b6203f2cac67693.

$ git log f37f51218..c8437bfa4 --date=short --format='%ad %ae %s' | sed 's/@chromium\.org//'
2014-07-09 vadimsh Add --task-summary-json parameter to swarming.py collect.
2014-07-09 vadimsh Fix tuple unpack exception.

R=maruel@chromium.org
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=282349

[Vadim Sh., 2014-07-10 02:59:40]

I plan to make recipe changes that need --task-summary-json.

[M-A Ruel, 2014-07-10 11:38:54]

lgtm

[commit-bot: I haz the power, 2014-07-10 11:39:57]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/vadimsh@chromium.org/379193005/1

[commit-bot: I haz the power, 2014-07-10 13:37:13]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  ios_dbg_simulator on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/ios_dbg_simulator/bui...)

[commit-bot: I haz the power, 2014-07-10 16:30:24]

Change committed as 282349