made basic ScriptExecution acceptance tests run under both debug and non-debug

This was extracted from my previous PR #803.

Given that we have quite different execution paths (different engines) for debug and non-debug I think it's worth making at least the basic execution acceptance tests run under both conditions.
It makes the scenario run twice, once with `true` passed as the argument to
the `debug` parameter and once with `false`. It's similar to Cucumber's
ScenarioOutline and Example mechanism.
On 23 Aug 2014 20:43, "Filip W" <notifications@github.com> wrote:

> In test/ScriptCs.Tests.Acceptance/ScriptExecution.cs:
>
> >
> >              "Then I see 'Hello world!'"
> >                  .f(() => output.ShouldContain("Hello world!"));
> >          }
> >
> >          [Scenario]
> > -        public static void ScriptThrowsAnException(ScriptFile script, Exception ex)
> > +        [Example(true)]
> > +        [Example(false)]
>
> what is this doing (two attributes)?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/scriptcs/scriptcs/pull/807/files#r16632406>.
>