[COOK-3959] - Add support for Mac OS X to users cookbook

Signed-off-by: Sean OMeara <someara@opscode.com>
[COOK-4078] - users cookbook fails in why-run mode for .ssh directory

Signed-off-by: Sean OMeara <someara@opscode.com>
[COOK-4139] - users_manage resource always notifies

Signed-off-by: Sean OMeara <someara@opscode.com>
updating .gitignore