benchmarks: allow custom base for visualization/output urls
benchmarks: allow custom base for visualization/output urls

This makes allows generating the plots and analysis data with links to
non-moose project commits rather than having the moose github url
hard-coded into benchmark.py.

ref #9834

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