batman-adv-specific parts are moved to a new package
gluon-status-page-mesh-batman-adv.

All Access-Control-Allow-Origin are removed to improve users' privacy. As
the status page API is thus not useful without the status page anymore,
merge them back into a single package.

The status-page-api respondd provider is removed as well.

Fixes #1194

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

This will make it easier to replace the API with C programs.

Apart from replacing a patch for the former by two patches for latter,
this involved minimal adaptations of the lua scripts in the following
packages:

* gluon-announce
* gluon-announced
* gluon-mesh-batman-adv-core
* gluon-status-page