Fix hex-fiend with chmod go=u

Hex Fiend does not correct set 'group' and 'other' permissions and will crash if
a non-owner runs it. The buggy files are fixed by updating their 'group' and
'other' permissions to reflect the 'user' permissions: chmod go=u.

Casks/hex-fiend.rb

@@ -8,4 +8,8 @@ cask :v1 => 'hex-fiend' do
   license :bsd
 
   app 'Hex Fiend.app'
+
+  postflight do
+    system '/bin/chmod', '-R', 'og=u', "#{staged_path}/Hex Fiend.app/Contents/Frameworks/Sparkle.framework"
+  end
 end