LXC: normalize package installation & user creation.

utils/lib.sh:
- get DIST_ID & DIST_VERSION from /etc/os-release
- pkg_[install|remove|...] supports ubuntu, debian, archlinux & fedora

utils/lxc.sh
- Workaround for the "setrlimit(RLIMIT_CORE): Operation not permitted" error::
    'Set disable_coredump false' >> /etc/sudo.conf

utils/[searx.sh|filtron.sh|morty.sh]
- switched user creation from 'adduser' perl script to 'useradd' built-in
  command

utils/searx.sh
- install packages for ubuntu, debian, archlinux & fedora

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

utils/filtron.sh

@@ -106,7 +106,7 @@ main() {
     rst_title "$SERVICE_NAME" part
 
     required_commands \
-        dpkg apt-get install git wget curl \
+        sudo install git wget curl \
         || exit
 
     local _usage="unknown or missing $1 command $2"
@@ -231,9 +231,11 @@ assert_user() {
     rst_title "user $SERVICE_USER" section
     echo
     tee_stderr 1 <<EOF | bash | prefix_stdout
-sudo -H adduser --shell /bin/bash --system --home $SERVICE_HOME \
-    --disabled-password --group --gecos 'Filtron' $SERVICE_USER
-sudo -H usermod -a -G shadow $SERVICE_USER
+useradd --shell /bin/bash --system \
+ --home-dir "$SERVICE_HOME" \
+ --comment 'Reverse HTTP proxy to filter requests' $SERVICE_USER
+mkdir "$SERVICE_HOME"
+chown -R "$SERVICE_GROUP:$SERVICE_GROUP" "$SERVICE_HOME"
 groups $SERVICE_USER
 EOF
     SERVICE_HOME="$(sudo -i -u "$SERVICE_USER" echo \$HOME)"