[COOK-3822] - Fixing up sasl_relayhost example in README

Signed-off-by: Sean OMeara <someara@opscode.com>
[COOK-3824] - Fixing up list construction in main.cf.erb

Signed-off-by: Sean OMeara <someara@opscode.com>
updating Gemfile with testing bits
cutting rubocop offenses down to 32
Version bump to v3.0.4
Merge branch 'master' of https://github.com/opscode-cookbooks/postfix