Wiki & Files for Sentry Droid

[kresty]

I posted a "stub" for the Sentry Droid on the wiki, it was a really quick thing, feel free to improve.  I suspect it'll need split up if we go further with it.

Additionally, don't forget the great files we have now in the Sentry Droid Files section of the gallery.

And of course Sentry Droid reference images, in that section of the gallery - but I owe some more pix for it.

[kresty]

I've added photos to the sentry droid reference photos....