Exception shown in logs as WARN when security group does not exist

[tbatchelli]

When creating a node for a security group that does not yet exist, an exception is thrown in the logs as a WARN which makes it look like something is broken, when this is a normal situation:

09:28:08.630 WARN  c.p.aws.api - process-aws-request error
com.amazonaws.AmazonServiceException: Status Code: 400, AWS Service: AmazonEC2, AWS Request ID: 3fdfef81-52da-4ee3-8cec-378ea2365761, AWS Error Code: InvalidGroup.NotFound, AWS Error Message: The security group 'pallet-from-package-centos-6-5' does not exist
    at com.amazonaws.http.AmazonHttpClient.handleErrorResponse(AmazonHttpClient.java:753) ~[aws-java-sdk-1.6.4.jar:na]
    at com.amazonaws.http.AmazonHttpClient.executeHelper(AmazonHttpClient.java:414) ~[aws-java-sdk-1.6.4.jar:na]
    at com.amazonaws.http.AmazonHttpClient.execute0(AmazonHttpClient.java:266) ~[aws-java-sdk-1.6.4.jar:na]
    at com.amazonaws.http.AmazonHttpClient.execute(AmazonHttpClient.java:236) ~[aws-java-sdk-1.6.4.jar:na]
    at com.amazonaws.services.ec2.AmazonEC2Client.invoke(AmazonEC2Client.java:6302) ~[aws-java-sdk-1.6.4.jar:na]
    at com.amazonaws.services.ec2.AmazonEC2Client.describeSecurityGroups(AmazonEC2Client.java:1061) ~[aws-java-sdk-1.6.4.jar:na]