[COOK-213] ruby: skip additional package installation when empty list
[COOK-213] ruby: skip additional package installation when empty list

pcreux/cookbooks,DataDog/opscode-cookbooks,beni55/cookbooks,gravitystorm/cookbooks,beni55/cookbooks,dbroeglin/cookbooks,dbroeglin/cookbooks,dagolden/opscode-cookbooks,beni55/cookbooks,gravitystorm/cookbooks,dagolden/opscode-cookbooks,pcreux/cookbooks,DataDog/opscode-cookbooks,dbroeglin/cookbooks,pgroudas/cookbooks,pcreux/cookbooks,beni55/cookbooks,dagolden/opscode-cookbooks,pgroudas/cookbooks,beni55/cookbooks,beni55/cookbooks,gravitystorm/cookbooks,pgroudas/cookbooks,DataDog/opscode-cookbooks