parse 3rd field in slave list, pass as max_builds
parse 3rd field in slave list, pass as max_builds

edunham/rust-buildbot,edunham/rust-buildbot,edunham/rust-buildbot,rust-lang-deprecated/rust-buildbot,rust-lang/rust-buildbot,rust-lang-deprecated/rust-buildbot,rust-lang/rust-buildbot,aidanhs/rust-buildbot,aidanhs/rust-buildbot,rust-lang/rust-buildbot,aidanhs/rust-buildbot,rust-lang-deprecated/rust-buildbot