remove luci-theme-bootstrap-piraten

We don't use the theme and don't want to maintain it in the future.
remove luci-theme-pberg

We don't use this theme and don't want to maintain it in the future.
remove fff2kamikaze

This upgrad path is not relevant for us anymore.
remove ssl-cert

We do not want one key/cert for all routers.
remove kerln packages

If someone needs extra packages for super specific routers they should create a
new repo and include this repo into a custom build/feeds.conf.
remove libesmtp
remove ubus

Should be part of openwrt by now.
remove motion package
README: change issue url