terminate_instance script for ec2 is deleting more than desired

[jwmatthews]

I had several instances provisioned that had a tag consisting of "jwm".
Some of the instances were from the multi-node work, so I had node01-jwm, node02-jwm, master-jwm.

In addition I had a single node, jwm.ec2.dog8code.com.

I ran terminate_instance.sh in the minimal directory, assumed that only the single node, jwm.ec2.dogcode.com would be terminated, but looks like all of the nodes which had 'jwm' in the tag were deleted.

We should re-examine the tagging and terminate behavior between single node in ec2 and multi node.