[Orgmode] slight change to default value of org-beamer-fragile-re

[Eric Schulte]

Hi,

I'd propose changing the default value of `org-beamer-fragile-re' from

  "^[ \t]*\\\\begin{verbatim}"

to

  "^[ \t]*\\\\begin{\\(verbatim\\|lstlisting\\)}"

as there are many ways in which Org-mode files automatically generate
lstlisting environments.

Best -- Eric