updated gitignore list to include `.grunt` folder
updated gitignore list to include `.grunt` folder

markbrouch/generator-yeogurt,markbrouch/generator-yeogurt,larsonjj/generator-yeogurt,OnkelTem/generator-yeogurt,dgoncalves1/generator-yeogurt,dgoncalves1/generator-yeogurt,jacekpolak/generator-yeogurt,OnkelTem/generator-yeogurt,larsonjj/generator-yeogurt,jacekpolak/generator-yeogurt