added ability to associate public ip to VPC instance on creation
added test for 'associate_public_ip' feature
added logging messages for public ips in vpc instances
added validation to ensure that associate public ip is only used in vpc mode
test for new associate public ip validation
added fog 1.16.0 dependency to knife-ec2.gemspec
Fix merge conflict, inter-example spec dependencies
Merge pull request #169 from opscode/adamed-knife-381

KNIFE-381: Add ability to associate public ip with VPC instance on creation