Making sure solution vectors are in sync in AuxiliarySystem (closes #2659).

This patch moves the calls solution().close() and _sys.update() right
after the element and nodal loop.  It also adds the same calls inbetween
volumetric and boundary loops, which caused these two vectors to be out
of sync resulting in incorrect values used in auxiliary boundary
conditions.
Merge pull request #2658 from andrsd/sync-solution-vectors

Making sure solution vectors are in sync in AuxiliarySystem.