Update Swarm Bot Setup Script to always stop on errors
Update Swarm Bot Setup Script to always stop on errors

Also use check_call when no input is specified, to allow sudo calls to get the password from the user.

R=maruel@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/11535009

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@172370 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build