V8 buildbot: reland usage of branches_cfg in slaves.cfg
V8 buildbot: reland usage of branches_cfg in slaves.cfg

The messup caused by doing the import outside the current directory was fixed by maruel in revision 97463. 
Review URL: http://codereview.chromium.org/8275028

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@106472 0039d316-1c4b-4281-b951-d872f2087c98

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