Add unit tests for use_iam_profile
Add unit tests for use_iam_profile

Test default value of use_iam_profile == nil
Test a connection is created without access keys while use_iam_profile
== true

ClogenyTechnologies/knife-ec2,MsysTechnologiesllc/knife-ec2,MsysTechnologiesllc/knife-ec2,juliandunn/knife-ec2,chef/knife-ec2,chef/knife-ec2,pallan/knife-ec2,paperlesspost/knife-ec2,4current/knife-ec2,evertrue/knife-ec2,TheNeatCompany/knife-ec2,cloudant/knife-ec2,tas50/knife-ec2