Added params keyword for aliases in VerbAttribute constructor

[rombethor]

Added params keyword to VerbAttribute constructor so that it can be used when forming the attribute as follows:

[Verb("my-command", false, "do", "the", "thing")]
public class MyCommandClass
{
   //does the thing
}

Closes #864

[ericnewton76]

A lot of build errors in the test project related to this change. Can we clean those up?

[rombethor]

I think we can close this without a merge. It was proven unnecessary in the issue #864