Ignore html files from Doxygen in git.
Ignore html files from Doxygen in git.

Refs #2986.

roystgnr/moose,liuwenf/moose,tonkmr/moose,waxmanr/moose,katyhuff/moose,zzyfisherman/moose,raghavaggarwal/moose,andrsd/moose,sapitts/moose,backmari/moose,permcody/moose,lindsayad/moose,milljm/moose,jinmm1992/moose,katyhuff/moose,lindsayad/moose,shanestafford/moose,roystgnr/moose,sapitts/moose,permcody/moose,milljm/moose,danielru/moose,yipenggao/moose,dschwen/moose,waxmanr/moose,stimpsonsg/moose,jhbradley/moose,dschwen/moose,SudiptaBiswas/moose,permcody/moose,tonkmr/moose,andrsd/moose,idaholab/moose,nuclear-wizard/moose,jessecarterMOOSE/moose,WilkAndy/moose,xy515258/moose,permcody/moose,zzyfisherman/moose,idaholab/moose,YaqiWang/moose,nuclear-wizard/moose,Chuban/moose,shanestafford/moose,stimpsonsg/moose,kasra83/moose,cpritam/moose,Chuban/moose,markr622/moose,jessecarterMOOSE/moose,jbair34/moose,WilkAndy/moose,backmari/moose,milljm/moose,liuwenf/moose,harterj/moose,joshua-cogliati-inl/moose,adamLange/moose,yipenggao/moose,katyhuff/moose,liuwenf/moose,andrsd/moose,markr622/moose,joshua-cogliati-inl/moose,wgapl/moose,capitalaslash/moose,jiangwen84/moose,harterj/moose,friedmud/moose,harterj/moose,raghavaggarwal/moose,jiangwen84/moose,wgapl/moose,roystgnr/moose,jinmm1992/moose,cpritam/moose,sapitts/moose,roystgnr/moose,jessecarterMOOSE/moose,xy515258/moose,katyhuff/moose,bwspenc/moose,capitalaslash/moose,lindsayad/moose,jessecarterMOOSE/moose,kasra83/moose,jiangwen84/moose,bwspenc/moose,backmari/moose,kasra83/moose,nuclear-wizard/moose,jasondhales/moose,adamLange/moose,sapitts/moose,harterj/moose,idaholab/moose,danielru/moose,apc-llc/moose,giopastor/moose,Chuban/moose,waxmanr/moose,cpritam/moose,jessecarterMOOSE/moose,tonkmr/moose,friedmud/moose,dschwen/moose,roystgnr/moose,giopastor/moose,yipenggao/moose,friedmud/moose,YaqiWang/moose,apc-llc/moose,mellis13/moose,backmari/moose,adamLange/moose,idaholab/moose,cpritam/moose,yipenggao/moose,WilkAndy/moose,jinmm1992/moose,giopastor/moose,roystgnr/moose,adamLange/moose,liuwenf/moose,giopastor/moose,andrsd/moose,laagesen/moose,joshua-cogliati-inl/moose,stimpsonsg/moose,YaqiWang/moose,jbair34/moose,jasondhales/moose,WilkAndy/moose,apc-llc/moose,tonkmr/moose,sapitts/moose,jbair34/moose,waxmanr/moose,dschwen/moose,markr622/moose,liuwenf/moose,mellis13/moose,SudiptaBiswas/moose,danielru/moose,jasondhales/moose,friedmud/moose,laagesen/moose,mellis13/moose,zzyfisherman/moose,shanestafford/moose,xy515258/moose,WilkAndy/moose,wgapl/moose,mellis13/moose,danielru/moose,SudiptaBiswas/moose,tonkmr/moose,shanestafford/moose,raghavaggarwal/moose,lindsayad/moose,laagesen/moose,shanestafford/moose,joshua-cogliati-inl/moose,idaholab/moose,jhbradley/moose,capitalaslash/moose,zzyfisherman/moose,stimpsonsg/moose,SudiptaBiswas/moose,SudiptaBiswas/moose,liuwenf/moose,laagesen/moose,jinmm1992/moose,YaqiWang/moose,raghavaggarwal/moose,wgapl/moose,kasra83/moose,bwspenc/moose,jhbradley/moose,jbair34/moose,jiangwen84/moose,zzyfisherman/moose,Chuban/moose,milljm/moose,zzyfisherman/moose,milljm/moose,cpritam/moose,capitalaslash/moose,jhbradley/moose,lindsayad/moose,andrsd/moose,markr622/moose,xy515258/moose,jasondhales/moose,bwspenc/moose,bwspenc/moose,dschwen/moose,cpritam/moose,apc-llc/moose,nuclear-wizard/moose,shanestafford/moose,tonkmr/moose,laagesen/moose,WilkAndy/moose,roystgnr/moose,harterj/moose