use env[:machine] for vagrant enable/disable

this allows you to specify on a per box basis if berkshelf is enabled or disabled
Merge pull request #92 from danshultz/disable_berkshelf_per_box

use env[:machine] for vagrant enable/disable
pass only/except options to vendor in install action
use config local to machine for deriving install options
Merge pull request #95 from RiotGames/pass-options-to-vendor

pass only/except options to vendor in install action