update readme for inet_interfaces and set nil as default
release v2.1.0
Include the proper sasl plain packages cite: http://sendgrid.com/docs/Integrate/Mail%20Servers/postfix.html
Merge pull request #17 from trobrock/COOK-2010

Include the proper sasl plain packages
release v2.1.2
[COOK-2281] postfix aliases uses require_recipe statement yet, should be include_recipe.
Merge pull request #19 from higanworks-cookbooks/FC042_require_recipe_is_deprecated

[COOK-2281] postfix aliases uses require_recipe statement yet, should be include_recipe.
release v2.1.4