Issues processing LogicalID for Softlayer instances

[kaufers]

The current LogicalID processing in the terraform instance provider has two issues:

• The "LogicalID" tag is only added to the tags if the tags object type is map but, for Softlayer, the tags object type is a list; this causes the LogicalID to never be added as a tag. Then, when the group plugin issues a DescribeInstances by group name, the instances returned have no LogicalID set -- and then the group plugin requests to create another instance.
• Softlayer only supports lower-case chars in tags so the code that looks for "LogicalID" in the tags will never match; this needs to be updated to implement a case-insensitive key check