Remove calls to SHAMapNode::getID

This addresses RIPD-347
Calls in SHAMap::getCache and SHAMap::canonicalize are
purposefully left in place at this time (to be removed
later).
Agreed.  And the "issue" with VS 2013 is not a bad one.  Worst case the constructor gets called twice... you don't get memory corruption.  The only possibility of error is if you take addresses of your return values and then compare them.