[COOK-3617] Fix no method chomp on NilClass attribute errors
[COOK-3617] Fix no method chomp on NilClass attribute errors

    The hostname/myhost/mydomain attributes try to chomp on a `nil` value, mainly the node["domain"] attribute. Additionally, || is used after a chomp, so empty string values will probably never hit the second half of the statement.

Signed-off-by: Seth Vargo <81550dbf04dfd8537ff7b3c014c6fbf86e0889dc@gmail.com>

chrisjbray/postfix,nilroy/postfix,mlyndaker/postfix,petere/postfix,Lostmyname/postfix,mawatech/postfix,opscode-cookbooks/postfix,zuazo-forks/chef-cookbooks-postfix,heat-cookbooks/postfix,mawatech/postfix,interactive-investor-ltd/postfix,rackspace-cookbooks/rackspace_postfix,rafaelmagu/postfix,nilroy/postfix,heat-cookbooks/postfix,yakara-ltd/postfix,tas50/postfix,i11/postfix,Lostmyname/postfix,leoditommaso/postfix,tejaycar/postfix,Maks3w/postfix,elliotkendallUCSF/postfix,voroniys/postfix,VertiPub/postfix,chrisjbray/postfix,zuazo-forks/chef-cookbooks-postfix,chef-cookbooks/postfix,gnowxilef/cookbook-postfix,voroniys/postfix,ianneub/postfix,opscode-cookbooks/postfix,yakara-ltd/postfix,interactive-investor-ltd/postfix,CarnegieLearningWeb/chef-postfix,mlyndaker/postfix,tezz123/postfix,leoditommaso/postfix,tcroiset/postfix,chef-cookbooks/postfix,CarnegieLearningWeb/chef-postfix,harmdewit/postfix,brint/postfix,gnowxilef/cookbook-postfix