Revert of Replaced boto certificate (https://codereview.chromium.org/212993005/)

Reason for revert:
This causes download_from_google_storage to fail:
Failure: CA certificates file does not have expected SHA1 sum; expected: ed024a78d9327f8669b3b117d9eac9e3c9460e9b, actual: 433e5589520cd2f1f29dea3e077cfbc2b74fb78c.

You'll need to also update the expectations on the gsutil side, and then reland.

Test it by running "gsutil ls".

Original issue's description:
> Replaced boto certificate
> 
> BUG=348233
> 
> Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=259692

TBR=stip@chromium.org,rsleevi@chromium.org,pgervais@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=348233

Review URL: https://codereview.chromium.org/213963002

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@259744 0039d316-1c4b-4281-b951-d872f2087c98

third_party/boto/README.chromium

@@ -36,7 +36,6 @@ Modifications:
 * Removed boto/.travis.yml
 * Removed boto/Changelog.rst
 * Removed boto/MANIFEST.in
-* Replaced boto/cacerts/cacerts.txt by file from http://pki.google.com/roots.pem
 * Moved boto down to be a first level directory
 
 Full license is in the LICENSE file.