Fix --user / -u argument when using st2 key delete command.
Fix --user / -u argument when using st2 key delete command.

nzlosh/st2,lakshmi-kannan/st2,nzlosh/st2,pixelrebel/st2,pixelrebel/st2,peak6/st2,pixelrebel/st2,nzlosh/st2,StackStorm/st2,lakshmi-kannan/st2,peak6/st2,StackStorm/st2,Plexxi/st2,punalpatel/st2,nzlosh/st2,Plexxi/st2,Plexxi/st2,tonybaloney/st2,tonybaloney/st2,StackStorm/st2,tonybaloney/st2,punalpatel/st2,punalpatel/st2,peak6/st2,Plexxi/st2,lakshmi-kannan/st2,StackStorm/st2