Added --config-file option; fixed some typos; use parser.error() in args validation
Added --config-file option; fixed some typos; use parser.error() in args validation

jamesblunt/nodeenv,asottile/nodeenv,chriskuehl/nodeenv,twmt/nodeenv,Milstein/nodeenv,simudream/nodeenv,jamesblunt/nodeenv,Milstein/nodeenv,jhermann/nodeenv,chriskuehl/nodeenv,simudream/nodeenv,asottile/nodeenv,twmt/nodeenv