Roll tools/swarming_client/ to 2558daf70a0eb67cc15eb8f7b7f885347523e77c.

Roll tools/swarming_client/ to 2558daf70a0eb67cc15eb8f7b7f885347523e77c.

$ git log 5b827c923..2558daf70 --date=short --format='%ad %ae %s' | sed 's/@chromium\.org//'
2014-11-25 vadimsh Make a class that executes HTTP requests replaceable.
2014-11-25 maruel Fix all client tests to succeed on Swarming on all platforms.
2014-11-24 vadimsh Remove test_get_http_service test.
2014-11-24 maruel Fix tools/run_swarming_tests_on_swarming.py.
2014-11-24 maruel Fix bug in 094f1a9e569c4cbeaf06358ccf9eabe75d938288.
2014-11-21 maruel When extract_resource() temp_dir != None, used a content addressed name.
2014-11-21 maruel Disable caching on file_path.listdir() for now.
2014-11-19 maruel Fix swarming.py bots with 8a7d6202fac84ec2276f98dd06caa3a2856b58c1
2014-11-17 maruel Remove unneeded python26_polyfill.py, add missing LICENSE.

R=vadimsh@chromium.org
BUG=

Review URL: https://codereview.chromium.org/760623004

Cr-Commit-Position: refs/heads/master@{#305856}