Add beamer class options.

* style/beamer.el: Update copyright years and remove trailing
whitespaces.
("beamer"): Run style hooks for loaded packages.
(LaTeX-beamer-class-options): New function.

* style/hyperref.el (LaTeX-hyperref-package-options-list): Rename
from `LaTeX-hyperref-package-options' to avoid clash with the
function with the same name.
("hyperref"): Use it.
(LaTeX-hyperref-package-options): Ditto.