Roll tools/swarming_client/ to b8aeeaef087fa2571aaaf64a8a8dbec06a0e0e41.

Roll tools/swarming_client/ to b8aeeaef087fa2571aaaf64a8a8dbec06a0e0e41.

$ git log bbf1fcca7..b8aeeaef0 --date=short --format='%ad %ae %s' | sed 's/@chromium\.org//'
2014-08-15 maruel Greatly improve subprocess42.
2014-08-15 maruel Fix parallel_execution which would pass the wrong argument in case of error.
2014-08-15 maruel Fix bugs in run_swarming_tests_on_swarming.py.
2014-08-15 maruel R.I.P. googletest/
2014-08-15 maruel Add callback support in net_utils.py when evaluation http request mock.
2014-08-14 maruel Fix third regression introduced in 0a62061f6e8e3f.
2014-08-13 maruel Fix second regression introduced in 0a62061f6e8e3f.
2014-08-13 maruel Fix regression introduced in 0a62061f6e8e3f.
2014-08-13 maruel Make json API url request saner.
2014-08-06 maruel Add .mp4 as already-compressed extension.

R=csharp@chromium.org
BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=290041

[csharp, 2014-08-15 18:22:41]

lgtm

[M-A Ruel, 2014-08-15 18:49:16]

The CQ bit was checked by maruel@chromium.org

[commit-bot: I haz the power, 2014-08-15 18:52:04]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/maruel@chromium.org/481523002/1

[commit-bot: I haz the power, 2014-08-15 23:11:29]

Committed patchset #1 (1) as 290041