This adds the wireless client count for 2.4GHz and 5 GHz radios to the
status page. Previously, only the total client count advertised by
the mesh protocol was visible.

This reverts commits
- caf2dd03.
- 07ebac6a
- 55eff45f

I accidentally pushed these commits as I had them lying around on a
dirty checkout I did testing on.

Fixes: #659
Signed-off-by: Martin Weinelt <martin@darmstadt.freifunk.net>

The field was accidentally removed during the status-page rewrite.

Fixes #1401

This new status page is significantly smaller than the old one. It always
loads its resources from the same host as the page itself, not requiring
cross-origin requests anymore.

It also uses the common i18n infrastructure of gluon-web.

Fixes #914