Making zip and bzip2 dependecies conditional
Making zip and bzip2 dependecies conditional

Here, we are adding `unless which("zip")` and `unless which("bzip2")`
and, thus, make `zip` and `bzip2` dependencies conditional.

mgrimes/brew,DomT4/brew,nandub/brew,Linuxbrew/brew,alyssais/brew,sjackman/homebrew,maxim-belkin/brew,nandub/brew,konqui/brew,EricFromCanada/brew,mahori/brew,MikeMcQuaid/brew,reitermarkus/brew,EricFromCanada/brew,DomT4/brew,MikeMcQuaid/brew,JCount/brew,vitorgalvao/brew,Homebrew/brew,konqui/brew,Linuxbrew/brew,JCount/brew,mahori/brew,konqui/brew,mahori/brew,mgrimes/brew,JCount/brew,mahori/brew,Linuxbrew/brew,MikeMcQuaid/brew,EricFromCanada/brew,ilovezfs/brew,hanxue/linuxbrew,DomT4/brew,reitermarkus/brew,alyssais/brew,DomT4/brew,hanxue/linuxbrew,Homebrew/brew,nandub/brew,mgrimes/brew,maxim-belkin/brew,konqui/brew,reitermarkus/brew,vitorgalvao/brew,reitermarkus/brew,claui/brew,claui/brew,Homebrew/brew,claui/brew,vitorgalvao/brew,sjackman/homebrew,ilovezfs/brew,ilovezfs/brew,alyssais/brew,JCount/brew,Homebrew/brew,EricFromCanada/brew,MikeMcQuaid/brew,hanxue/linuxbrew,maxim-belkin/brew,claui/brew,Linuxbrew/brew,vitorgalvao/brew,sjackman/homebrew,sjackman/homebrew,nandub/brew