Do not use ARN as profile_name when connecting using boto

Using latest boto I got 

    boto.provider.ProfileNotFoundError: Profile "arn:aws:iam::xxx:instance-profile/xxx not" found!

As per @danielgtaylor's comment here https://github.com/sebdah/dynamic-dynamodb/issues/183#issuecomment-45389879 I patched aws-ec2-assign-elastic-ip to not send the ARN as profile name when using instance metadata to connect to AWS through boto.

Also bumped the requirement on boto to latest version as this behavior was allowed (unintentionally in boto <2.29.x).