add attribute formatting for better stats

[turowicz]

Enables to write code like this:

public class FooService : IFooService
{
    [StatsDCounting("dependencies.{type}.{method}")]
    [StatsDTiming("dependencies.{type}.{method}")]
    public void TrackedFormattedMethod()
    {
    }

    [StatsDCounting("dependencies.{generic}")]
    [StatsDTiming("dependencies.{generic}")]
    public T TrackedGenericMethod<T>()
    {
        return default(T);
    }
}

[turowicz]

@andyroyle tell me what you think

[turowicz]

I only really need the generic part, so if you think performance is at risk, we can remove the type and method bits.

[andyroyle]

it's not really a huge performance hit. Yes it's reflection, but we're already doing some reflection to get the method attributes, so it's not a huge extra hit.

Looks good to me dude!

👍