add a new policy for create keypair

haram:sendak jane$ aws iam put-user-policy --user-name gregboone --policy-name 'ec2-create-public-key-pair' --policy-document file://etc/aws_policies/ec2-create-keypair.json
haram:sendak jane$ aws iam get-user-policy --user-name gregboone --policy-name 'ec2-create-public-key-pair'
{
    "UserName": "gregboone",
    "PolicyName": "ec2-create-public-key-pair",
    "PolicyDocument": {
        "Version": "2012-10-17",
        "Statement": [
            {
                "Action": [
                    "ec2:DescribeKeyPairs",
                    "ec2:CreateKeyPair"
                ],
                "Resource": "*",
                "Effect": "Allow"
            }
        ]
    }
}

gboone verified this works to create keypairs.

TODO: note that this does not allow one to upload a keypair; i'm not sure which bit needs to be flipped for that.