Add Options<T>

[davidfowl]

Would act as an IOptions<T> wrapper for some T. Would make a convenient way to create an IOptions<T> from any T. We could also have a factory method (/cc @divega) that makes one of these from a T i.e. IOptions<T> Options.Create<T>(T options).

[HaoK]

Would this would be instead of the old pattern of MyOptions implementing IOptions<MyOptions>?

[davidfowl]

Yep! It's something @PinpointTownes suggested #105 (comment).

[davidfowl]

I updated the sample in B to show the usage.

[HaoK]

Ok yeah that looks much better, it was pretty gross making everything implement IOptions before... Maybe we should name the generic Options class OptionsWrapper so people don't think its a base class...which is what the name implies...

[davidfowl]

PR out for review.

[HaoK]

Do we want to consider an overload of Options.Create<T>(Action<T> configure) just as pure sugar?

[davidfowl]

Hmmmmmmmm

[davidfowl]

app.UseFoo(Options.Create(options =>
{
    options.Value = 10;
});

var options = Options.Create(opt =>
{
  opt.Value = 10;
});

app.UseFoo(options);

[HaoK]

Yeah well this way you give people the option to do either one, so everyone is happy