Fix command execution in mac osx (#670)

scripts/setup_sumo_osx.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 echo "Installing system dependencies for SUMO"
 # Quick check that we actually have brew, if not, lets install it
-command -v brew >/dev/null 2>&1 || echo >&2 "Homebrew is missing, you can install it by running `/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)`" || exit 1
+command -v brew >/dev/null 2>&1 || echo >&2 "Homebrew is missing, you can install it by running \n/usr/bin/ruby -e \$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)" || exit 1
 # script dependencies
 brew install wget
 # rllab dependencies