Improve error handling when executable is missing
Improve error handling when executable is missing

(closes #9655)

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