Fixed missing Hardware Ids

When the plugin sorted the Hardware Id results it discarded many of them for some providers (e.g. Rackspace) as duplicates because of the way the Guava ImmutableSortedSets worked with the jclouds HardwareImpl.compareTo() method.

Originally I tried using a Guava ImmutableSortedMultiset instead but strangely duplicates objects when compareTo() returns 0. 

Just sorting a List turned out to be the right way to do it so that order is preserved but no Hardware Ids are discarded.