Convert str to int
Convert str to int

tester.exit_code needs to be an int, otherwise a str comparison
will always produce a failure (CRASH).

Closes #10689

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