Fix layout for rockstar-speakers section.
Fix layout for rockstar-speakers section.

The speakers in the rockstar section are generated via JS as follows:

1. It gets a list of speakers to show.
2. Sorts it randomly.
3. Adds each speaker after the prior element reversing it. Adds clearfixes at
   will and some other crap too.

Trying to center the last element is a bit hard with current setting.

src-d/talks,src-d/talks,src-d/talks,src-d/talks