Adding an empty constructor to DittoMultiProcessorAttribute

[jamiepollock]

During Code Cabin 16 (woo #codecabin16!) @mattbrailsford asked us to remind him to add an empty constructor to DittoMultiProcessorAttribute. Instead I've added in the code myself (feature sniping! :/)

The reason for this was to allow more sophisticated parameter/property binding through the inherited DittoMultiProcessorAttribute.

Example of this would be the following.

    public class TitleAttribute : DittoMultiProcessorAttribute
    {
        public string TitlePropertyAlias { get; set; }

        public TitleAttribute()
        {
            base.Attributes.AddRange(new[]
            {
                new UmbracoPropertyAttribute(TitlePropertyAlias),
                new AltUmbracoPropertyAttribute("Name")
            });
        }
    }

Where as the traditional way to achieve a similar thing would be:

    public class TitleAttribute : DittoMultiProcessorAttribute
    {
        public TitleAttribute(string titlePropertyAlias) : base(new[]
        {
            new UmbracoPropertyAttribute(titlePropertyAlias),
            new AltUmbracoPropertyAttribute("Name")
        })
        {

        }
    }

This is a fairly simple example but there could be better uses with this new flexibility. I've also added in a unit test to prove out the results of a traditional DittoMultiProcessorAttribute is the same as the new empty constructor DittoMultiProcessorAttribute.

[leekelleher]

Thanks @jamiepollock ... go grab a :beer: from the fridge!

[jamiepollock]

@leekelleher collaboration tastes good! Cheers mate :)