Adding listNodesByIds across the board.

Adding to both ListNodesStrategy and ComputeServiceAdapter. When
possible, does a query explicitly for the specified IDs. When not,
falls back on either listDetailsOnNodesMatching (for ListNodesStrategy
implementations and in BaseComputeService) or filters listNodes output
itself (in ComputeServiceAdapter).
Merge pull request #1507 from jclouds/listnodesdetails-1.6.x

Adding listNodesByIds across the board. (1.6.x)