Fix gem install help for brew-server
Fix gem install help for brew-server

Sinatra gem must be installed for the system ruby.

DomT4/brew,vitorgalvao/brew,amar-laksh/brew_sudo,AnastasiaSulyagina/brew,ilovezfs/brew,hanxue/linuxbrew,ilovezfs/brew,nandub/brew,jmsundar/brew,sjackman/homebrew,MikeMcQuaid/brew,nandub/brew,muellermartin/dist,palxex/brew,zmwangx/brew,DomT4/brew,alyssais/brew,reelsense/brew,vitorgalvao/brew,palxex/brew,muellermartin/dist,DomT4/brew,claui/brew,bfontaine/brew,tonyg/homebrew,aw1621107/brew,mistydemeo/homebrew,pseudocody/brew,konqui/brew,alyssais/brew,claui/brew,EricFromCanada/brew,DomT4/brew,maxim-belkin/brew,Homebrew/brew,pseudocody/brew,amar-laksh/brew_sudo,zmwangx/brew,alyssais/brew,reitermarkus/brew,MikeMcQuaid/brew,hanxue/linuxbrew,nandub/brew,konqui/brew,JCount/brew,rwhogg/brew,mahori/brew,rwhogg/brew,staticfloat/brew,tonyg/homebrew,pseudocody/brew,vitorgalvao/brew,Homebrew/brew,mahori/brew,mahori/brew,mgrimes/brew,sjackman/homebrew,tonyg/homebrew,nandub/brew,konqui/brew,maxim-belkin/brew,mgrimes/brew,gordonmcshane/homebrew,Linuxbrew/brew,MikeMcQuaid/brew,mgrimes/brew,Homebrew/brew,mistydemeo/homebrew,jmsundar/brew,sjackman/homebrew,EricFromCanada/brew,maxim-belkin/brew,reitermarkus/brew,JCount/brew,ilovezfs/brew,Homebrew/brew,Linuxbrew/brew,JCount/brew,reitermarkus/brew,muellermartin/dist,reitermarkus/brew,amar-laksh/brew_sudo,staticfloat/brew,gordonmcshane/homebrew,mistydemeo/homebrew,gregory-nisbet/brew,JCount/brew,EricFromCanada/brew,jmsundar/brew,MikeMcQuaid/brew,gordonmcshane/homebrew,gregory-nisbet/brew,zmwangx/brew,hanxue/linuxbrew,reelsense/brew,claui/brew,Linuxbrew/brew,toonetown/homebrew,reelsense/brew,vitorgalvao/brew,EricFromCanada/brew,konqui/brew,claui/brew,toonetown/homebrew,mahori/brew,palxex/brew,aw1621107/brew,sjackman/homebrew,toonetown/homebrew,rwhogg/brew,Linuxbrew/brew,staticfloat/brew,aw1621107/brew,AnastasiaSulyagina/brew,gregory-nisbet/brew,bfontaine/brew,bfontaine/brew,AnastasiaSulyagina/brew