Show names for confirmed talks

If a talk is confirmed and we can see the agenda then show the proposers name on the selections page and the proposal page.

We also explain why the name is shown on the proposal page.

Looks a bit like (agenda page):

![Welcome __ Vestibule-1](https://f.cloud.github.com/assets/608/263781/71d8dbce-8d7b-11e2-83b1-5c402ce65282.jpg)

and (proposal page):

![The need for and usage of xpath for cucumber steps __ Vestibule](https://f.cloud.github.com/assets/608/263769/2c4a2a54-8d7b-11e2-8dd5-b611ccf459b9.jpg)