LuCI's authentication won't work without rpcd, but we aren't using the
authentication anyways. Users who need it can just install rpcd explicitly.

Fixes #452

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