brew-bundle: general cleanup.

Library/Contributions/cmd/brew-bundle.rb

-# Looks for a Brewfile and runs each line as a brew command. For example:
+# brew-bundle.rb
+# Looks for a "Brewfile" in the current directory and runs each line
+# as a brew command.
 #
+# For example, given a Brewfile with the following contents:
 # tap foo/bar
 # install spark
 #
-# Saving the above commands in a Brewfile and running `brew bundle` will run
-# the commands `brew tap foo/bar` and `brew install spark` automagically.
-#
-# Current discussion: https://github.com/mxcl/homebrew/pull/24107
+# Running `brew bundle` will run the commands `brew tap foo/bar`
+# and `brew install spark`.
+
+raise 'Cannot find Brewfile' unless File.exist? 'Brewfile'
 
-raise "Cannot find Brewfile" if not File.exist?('Brewfile')
 File.readlines('Brewfile').each do |line|
-	command = line.chomp
-	if not command.empty? and not command.chars.first == '#'
-		`brew #{command}`
-	end
+  command = line.chomp
+  next if command.empty?
+  next if command.chars.first == '#'
+
+  system "brew #{command}"
 end