Update instructions to install LLVM 3.5 using Homebrew
Update instructions to install LLVM 3.5 using Homebrew

Homebrew bumped the version of LLVM installed with `brew install llvm`
from 3.5.1 to 3.6.0. So now users will have to tap homebrew-versions and
run `brew install llvm35` in order to get the version necessary to
install recent versions of Rubinius. The 3.5-specific `llvm-config`
becomes `llvm-config-3.5` accordingly.

https://github.com/Homebrew/homebrew/commit/0196a069a01e455b61778d804ebb81f46e7c31ff

OiNutter/node-build,liquid/ruby-build,brigade/node-build,chiting/ruby-build,dark-panda/ruby-build,nodenv/node-build,jeremy/ruby-build,znz/ruby-build,mpalmer/puppet-module-ruby-build,makandra/ruby-build,jasonkarns/ruby-build,telstra-digital/ruby-build,deepj/ruby-build,andrew-christianson/ruby-build,rbenv/ruby-build,brigade/ruby-build,nirvdrum/ruby-build,pitr-ch/ruby-build,koic/ruby-build,ryanfb/ruby-build,pongstr/node-build,sstephenson/ruby-build,brigade/ruby-build,RinSer/ruby-build,dark-panda/ruby-build,cppforlife/ruby-build,reedloden/ruby-build,geoffharcourt/ruby-build,mpalmer/puppet-module-ruby-build,rbenv/ruby-build,Angeldude/ruby-build,keltia/ruby-build