Add grunt installation on Travis before_script hook
Add grunt installation on Travis before_script hook

youngmountain/generator-node-gulp,joeybaker/generator-iojs,iamstarkov/generator-node,canercandan/generator-node,RobertJGabriel/generator-node,ksheedlo/generator-node-mocha-jscs,rhettl/generator-node,davewasmer/generator-node,joeybaker/generator-iojs,morgante/generator-nodepack,yeoman/generator-node,liuxiong332/generator-node-gulp-coffee,thehobbit85/generator-node,zckrs/generator-node,amitport/generator-node,stevemao/generator-node