image-pruning: Improve help and error reporting
image-pruning: Improve help and error reporting

Signed-off-by: Michal Minář <ea3139ea422390c9a8bd6d7fb9ba423400fabbd1@redhat.com>

pravisankar/origin,maxamillion/origin,mrogers950/origin,ryanj/origin,xiuwang/origin,elyscape/origin,luciddreamz/origin,dobbymoodge/origin,deads2k/origin,liangxia/origin,nak3/origin,ingvagabund/origin,PI-Victor/origin,luciddreamz/origin,coreydaley/origin,maxamillion/origin,jwhonce/origin,spadgett/origin,liggitt/origin,ryanj/origin,danmcp/origin,liggitt/origin,nak3/origin,nhr/origin,Miciah/origin,markllama/origin,coreydaley/origin,deads2k/origin,pmorie/origin,JacobTanenbaum/origin,tnozicka/origin,legionus/origin,liangxia/origin,markllama/origin,PI-Victor/origin,wjiangjay/origin,jsafrane/origin,sg00dwin/origin,elyscape/origin,elyscape/origin,PI-Victor/origin,deads2k/origin,rajatchopra/origin,rajatchopra/origin,openshift/origin,php-coder/origin,PI-Victor/origin,mahak/origin,anpingli/origin,childsb/origin,rhamilto/origin,php-coder/origin,wjiangjay/origin,nhr/origin,pmorie/origin,rhamilto/origin,jsafrane/origin,jim-minter/origin,dobbymoodge/origin,luciddreamz/origin,pmorie/origin,pmorie/origin,hferentschik/origin,hferentschik/origin,bparees/origin,abutcher/origin,goern/origin,elyscape/origin,markllama/origin,sg00dwin/origin,php-coder/origin,goern/origin,imcsk8/origin,pweil-/origin,tnozicka/origin,JacobTanenbaum/origin,tnozicka/origin,bparees/origin,sg00dwin/origin,sferich888/origin,gabemontero/origin,wjiangjay/origin,php-coder/origin,luciddreamz/origin,childsb/origin,PI-Victor/origin,mahak/origin,jwhonce/origin,enj/origin,aveshagarwal/origin,rhamilto/origin,php-coder/origin,dgoodwin/origin,childsb/origin,nak3/origin,dinhxuanvu/origin,markllama/origin,ramr/origin,sallyom/origin,sdminonne/origin,raffaelespazzoli/origin,liangxia/origin,aveshagarwal/origin,ramr/origin,dgoodwin/origin,raffaelespazzoli/origin,ryanj/origin,pravisankar/origin,dgoodwin/origin,jwhonce/origin,hferentschik/origin,jwhonce/origin,jim-minter/origin,raffaelespazzoli/origin,hroyrh/origin,jeremyeder/origin,juanvallejo/origin,raffaelespazzoli/origin,mrogers950/origin,anpingli/origin,hferentschik/origin,aveshagarwal/origin,linzhaoming/origin,dgoodwin/origin,kargakis/origin,akram/origin,soltysh/origin,mkumatag/origin,mfojtik/origin,kargakis/origin,linzhaoming/origin,kargakis/origin,rhamilto/origin,dobbymoodge/origin,spadgett/origin,JacobTanenbaum/origin,sallyom/origin,sdminonne/origin,Miciah/origin,coreydaley/origin,danmcp/origin,jwhonce/origin,pravisankar/origin,mdshuai/origin,childsb/origin,sallyom/origin,childsb/origin,ryanj/origin,jwhonce/origin,kargakis/origin,aveshagarwal/origin,spadgett/origin,PI-Victor/origin,tnozicka/origin,linzhaoming/origin,mdshuai/origin,gabemontero/origin,dgoodwin/origin,ironcladlou/origin,sjug/origin,jsafrane/origin,hroyrh/origin,jeremyeder/origin,pecameron/origin,ironcladlou/origin,ramr/origin,liangxia/origin,ryanj/origin,dinhxuanvu/origin,legionus/origin,maxamillion/origin,pravisankar/origin,pecameron/origin,akram/origin,nhr/origin,openshift/origin,miminar/origin,abutcher/origin,xiuwang/origin,mdshuai/origin,pmorie/origin,tnozicka/origin,liangxia/origin,miminar/origin,abutcher/origin,rajatchopra/origin,legionus/origin,imcsk8/origin,Miciah/origin,juanvallejo/origin,hferentschik/origin,wjiangjay/origin,gabemontero/origin,jeremyeder/origin,danmcp/origin,juanvallejo/origin,nhr/origin,danmcp/origin,mahak/origin,markllama/origin,liangxia/origin,ingvagabund/origin,sjug/origin,mfojtik/origin,juanvallejo/origin,kargakis/origin,enj/origin,abutcher/origin,markllama/origin,mrogers950/origin,hferentschik/origin,openshift/origin,legionus/origin,bparees/origin,mdshuai/origin,sjug/origin,dinhxuanvu/origin,spadgett/origin,soltysh/origin,miminar/origin,anpingli/origin,csrwng/origin,jeremyeder/origin,liggitt/origin,linzhaoming/origin,mfojtik/origin,elyscape/origin,linzhaoming/origin,spadgett/origin,dobbymoodge/origin,miminar/origin,csrwng/origin,goern/origin,luciddreamz/origin,aveshagarwal/origin,pravisankar/origin,imcsk8/origin,soltysh/origin,sferich888/origin,imcsk8/origin,miminar/origin,wjiangjay/origin,mrogers950/origin,sdminonne/origin,liggitt/origin,jeremyeder/origin,mdshuai/origin,rajatchopra/origin,tnozicka/origin,php-coder/origin,childsb/origin,akram/origin,rajatchopra/origin,dobbymoodge/origin,pweil-/origin,ryanj/origin,abutcher/origin,dobbymoodge/origin,maxamillion/origin,ingvagabund/origin,nhr/origin,rajatchopra/origin,mkumatag/origin,miminar/origin,dinhxuanvu/origin,rhamilto/origin,sferich888/origin,mrogers950/origin,ironcladlou/origin,goern/origin,mkumatag/origin,liggitt/origin,imcsk8/origin,maxamillion/origin,imcsk8/origin,jim-minter/origin,csrwng/origin,ramr/origin,pweil-/origin,liggitt/origin,wjiangjay/origin,ramr/origin,juanvallejo/origin,juanvallejo/origin,mrogers950/origin,legionus/origin,kargakis/origin,pecameron/origin,sg00dwin/origin,dinhxuanvu/origin,mdshuai/origin,luciddreamz/origin,hroyrh/origin,enj/origin,xiuwang/origin