Remove deprecated brew commands (donnemartin#98)

@estyxx thank you!

Author: estyxx

brew.sh

@@ -31,10 +31,9 @@ brew install moreutils
 # Install GNU `find`, `locate`, `updatedb`, and `xargs`, `g`-prefixed.
 brew install findutils
 # Install GNU `sed`, overwriting the built-in `sed`.
-brew install gnu-sed --with-default-names
+brew install gnu-sed
 # Install Bash 4.
 brew install bash
-brew tap homebrew/versions
 brew install bash-completion2
 # We installed the new shell, now we have to activate it
 echo "Adding the newly installed shell to the list of allowed shells"