github_packages: add helper class methods.
github_packages: add helper class methods.

JCount/brew,EricFromCanada/brew,vitorgalvao/brew,JCount/brew,EricFromCanada/brew,MikeMcQuaid/brew,JCount/brew,MikeMcQuaid/brew,nandub/brew,Homebrew/brew,Homebrew/brew,EricFromCanada/brew,claui/brew,JCount/brew,Homebrew/brew,claui/brew,nandub/brew,vitorgalvao/brew,Homebrew/brew,claui/brew,MikeMcQuaid/brew,nandub/brew,sjackman/homebrew,vitorgalvao/brew,EricFromCanada/brew,sjackman/homebrew,claui/brew,sjackman/homebrew,sjackman/homebrew,vitorgalvao/brew,nandub/brew,MikeMcQuaid/brew