Fix brew cask style with relative paths.

Library/Homebrew/cask/cmd/style.rb

@@ -31,7 +31,7 @@ module Cask
         @cask_paths ||= if args.empty?
           Tap.map(&:cask_dir).select(&:directory?)
         elsif args.any? { |file| File.exist?(file) }
-          args
+          args.map { |path| Pathname(path).expand_path }
         else
           casks.map(&:sourcefile_path)
         end

Library/Homebrew/test/cask/cmd/style_spec.rb

@@ -106,7 +106,10 @@ describe Cask::Cmd::Style, :cask do
       end
 
       it "treats all tokens as paths" do
-        expect(subject).to eq(tokens)
+        expect(subject).to eq [
+          Pathname("adium").expand_path,
+          Pathname("Casks/dropbox.rb").expand_path,
+        ]
       end
     end