Improvement for social icons in about.html (#41)
* Apply aria-hidden to the whole list of social icons since it also affects
all descendants. Thus, the code becomes a bit shorter. See
http://stackoverflow.com/a/18933265 for more details.
* Shorten code for including social icons. This way icon packs which are
included via `custom_css` are also supported.
Signed-off-by: Stephan Kulla <git.mail@kulla.me>