Add 40 new win7 slaves to the try server.
Add 40 new win7 slaves to the try server.

Those bots are faster and have more disk space, so they will
be used for both win_aura and the default bots.

TBR=maruel
Review URL: https://codereview.chromium.org/11412159

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@169396 0039d316-1c4b-4281-b951-d872f2087c98

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