postfix::config: fix augeas name.
postfix::config: fix augeas name.

An "invalid tag" error was thrown is the value was something like "[10.1.2.3]".
The trick was to surround the value with single quotes.
Thanks gmambro for the bug report.

craigwatson/puppet-postfix,saimonn/puppet-postfix,saimonn/puppet-postfix,alexjfisher/puppet-postfix,camptocamp/puppet-postfix,craigwatson/puppet-postfix,mcanevet/puppet-postfix,micah/puppet-postfix,camptocamp/puppet-postfix,mcanevet/puppet-postfix,alexjfisher/puppet-postfix,micah/puppet-postfix