Bugfix: custom elements are now display:block style.

Having the custom made elements (like favpod) not be block display
was causing some styling issues (padding wasn't being applied
properly when the bootstrap medium treshold was reached -- that is
with larger window width, all-podcasts element had padding, but
with smaller window width [below bootstrap medium columns
treshold], it didn't.

I don't think this has anything to do with the fact that the column
size was medium. Any column size except xs would have led to
similar issues as far as I can tell.