removing the speaker profile feature. It isn't used.

It's a pretty destructive pull request, do please run locally (including db patches) first, but it does seem to be fine for me.  I had to read the code to figure out how to route into this code, and google analytics shows zero hits to /speaker/anything this month so I'm confident we do not need this (and I don't think we should support it or encourage people to enter their personal details into this system).

Happy to have reviews, discussion and comments