Remove dependency on a private PETSc header file, petsc-private/snesimpl.h
Remove dependency on a private PETSc header file, petsc-private/snesimpl.h

Closes #7312

permcody/moose,idaholab/moose,friedmud/moose,permcody/moose,joshua-cogliati-inl/moose,backmari/moose,nuclear-wizard/moose,friedmud/moose,harterj/moose,yipenggao/moose,dschwen/moose,lindsayad/moose,katyhuff/moose,bwspenc/moose,laagesen/moose,andrsd/moose,yipenggao/moose,SudiptaBiswas/moose,dschwen/moose,backmari/moose,YaqiWang/moose,Chuban/moose,jessecarterMOOSE/moose,liuwenf/moose,bwspenc/moose,idaholab/moose,milljm/moose,stimpsonsg/moose,bwspenc/moose,lindsayad/moose,lindsayad/moose,permcody/moose,katyhuff/moose,Chuban/moose,laagesen/moose,YaqiWang/moose,stimpsonsg/moose,milljm/moose,stimpsonsg/moose,friedmud/moose,jessecarterMOOSE/moose,stimpsonsg/moose,laagesen/moose,andrsd/moose,katyhuff/moose,harterj/moose,harterj/moose,joshua-cogliati-inl/moose,joshua-cogliati-inl/moose,liuwenf/moose,sapitts/moose,sapitts/moose,laagesen/moose,bwspenc/moose,dschwen/moose,sapitts/moose,jessecarterMOOSE/moose,nuclear-wizard/moose,joshua-cogliati-inl/moose,Chuban/moose,milljm/moose,andrsd/moose,sapitts/moose,idaholab/moose,lindsayad/moose,sapitts/moose,lindsayad/moose,dschwen/moose,SudiptaBiswas/moose,andrsd/moose,laagesen/moose,milljm/moose,YaqiWang/moose,harterj/moose,friedmud/moose,liuwenf/moose,liuwenf/moose,idaholab/moose,YaqiWang/moose,andrsd/moose,yipenggao/moose,permcody/moose,katyhuff/moose,backmari/moose,backmari/moose,harterj/moose,liuwenf/moose,jessecarterMOOSE/moose,yipenggao/moose,SudiptaBiswas/moose,bwspenc/moose,Chuban/moose,SudiptaBiswas/moose,SudiptaBiswas/moose,nuclear-wizard/moose,milljm/moose,nuclear-wizard/moose,jessecarterMOOSE/moose,idaholab/moose,dschwen/moose,liuwenf/moose