NonlinearEigenSystem: don't close the matrix before solve
NonlinearEigenSystem: don't close the matrix before solve

if nonlinear eigenvalue solvers are chosen. The memory will be shrunk
and the preallocaiton will be removed if we close the matrix too early.

Refs #7398

laagesen/moose,YaqiWang/moose,nuclear-wizard/moose,sapitts/moose,jessecarterMOOSE/moose,harterj/moose,andrsd/moose,SudiptaBiswas/moose,sapitts/moose,idaholab/moose,YaqiWang/moose,milljm/moose,bwspenc/moose,laagesen/moose,harterj/moose,laagesen/moose,YaqiWang/moose,milljm/moose,laagesen/moose,harterj/moose,laagesen/moose,lindsayad/moose,jessecarterMOOSE/moose,permcody/moose,idaholab/moose,SudiptaBiswas/moose,bwspenc/moose,bwspenc/moose,andrsd/moose,andrsd/moose,sapitts/moose,milljm/moose,idaholab/moose,YaqiWang/moose,andrsd/moose,friedmud/moose,idaholab/moose,dschwen/moose,friedmud/moose,dschwen/moose,permcody/moose,friedmud/moose,SudiptaBiswas/moose,friedmud/moose,lindsayad/moose,harterj/moose,andrsd/moose,jessecarterMOOSE/moose,harterj/moose,bwspenc/moose,nuclear-wizard/moose,lindsayad/moose,idaholab/moose,dschwen/moose,lindsayad/moose,bwspenc/moose,dschwen/moose,SudiptaBiswas/moose,dschwen/moose,sapitts/moose,lindsayad/moose,milljm/moose,sapitts/moose,nuclear-wizard/moose,permcody/moose,permcody/moose,SudiptaBiswas/moose,nuclear-wizard/moose,milljm/moose,jessecarterMOOSE/moose,jessecarterMOOSE/moose