Add check args and print usage to st2ctl
Add check args and print usage to st2ctl

Add basic check args to st2ctl. If check args fail, st2ctl will print
usage information.

alfasin/st2,punalpatel/st2,tonybaloney/st2,Plexxi/st2,emedvedev/st2,Itxaka/st2,pixelrebel/st2,jtopjian/st2,Plexxi/st2,dennybaa/st2,emedvedev/st2,StackStorm/st2,Itxaka/st2,grengojbo/st2,emedvedev/st2,armab/st2,pinterb/st2,nzlosh/st2,tonybaloney/st2,dennybaa/st2,grengojbo/st2,alfasin/st2,nzlosh/st2,pixelrebel/st2,StackStorm/st2,jtopjian/st2,lakshmi-kannan/st2,jtopjian/st2,armab/st2,lakshmi-kannan/st2,peak6/st2,nzlosh/st2,Plexxi/st2,dennybaa/st2,pixelrebel/st2,StackStorm/st2,peak6/st2,armab/st2,nzlosh/st2,Plexxi/st2,pinterb/st2,StackStorm/st2,Itxaka/st2,punalpatel/st2,punalpatel/st2,pinterb/st2,tonybaloney/st2,peak6/st2,grengojbo/st2,alfasin/st2,lakshmi-kannan/st2