Updated LaunchConfig for AutoScaling UpdatePolicy

Updated LaunchConfig for AutoScaling UpdatePolicy

This is the first part of a series to implement support
for AutoScaling UpdatePolicy.

Updated LaunchConfiguration resource type to return
self.physical_resource_name() in FnGetRefId(). For both
InstanceGroup and AutoScalingGroup, the property
LaunchConfigurationName is added to the list of update allowed
properties. With this change, any property change to the
LaunchConfiguration resource will be result in a different
LaunchConfigurationName on reference resolution and thus will
trigger InstanceGroup and AutoScalingGroup to handle the update.

Change-Id: I94da8f7083b64873c511b953c6bc63dba2b51034
blueprint: as-update-policy