DNU shouldn't throw with bad args

[richlander]

DNU throws with bad args. It should fail more gracefully.

dotnet-mbp:dnulist richlander$ dnu upgrade
Specify --help for a list of available options and commands.
System.Exception: TODO: Error: unrecognized argument 'upgrade'
  at Microsoft.Framework.Runtime.Common.CommandLine.CommandLineApplication.HandleUnexpectedArg (Microsoft.Framework.Runtime.Common.CommandLine.CommandLineApplication command, System.String[] args, Int32 index, System.String argTypeName) [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.Runtime.Common.CommandLine.CommandLineApplication.Execute (System.String[] args) [0x00000] in <filename unknown>:0 
  at Microsoft.Framework.PackageManager.Program.Main (System.String[] args) [0x00000] in <filename unknown>:0 
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 

[davidfowl]

You just mean you don't want to see a stack trace.

[richlander]

Yes.

[Eilon]

Basically the same as aspnet/dnx#1923.

[muratg]

Dup of aspnet/dnx#1923