TT#36228 Depend on dbus + libpam-systemd

We would have preferred a solution without depending on dbus, but
only with usage of dbus/libpam-systemd we can leverage full usage
of systemd, e.g.:

* usage of systemctl as user
* usage of systemd-run
* user sessions get moved into proper cgroups
* remote host usage (like `systemctl --host=sp2 status foo.service`)
* hanging ssh sessions (depending on systemd version in usage,
  we ship a custom patch in our systemd backport for now which
  tries to work around it)
* working shutdown (without requiring `-h now`, as it defaults
  to '+1' by default, being a scheduled shutdown which works
  only with dbus)

Change-Id: I06284a948fbcb428195929af9d626dc6f5e3345b

debian/control

@@ -250,6 +250,7 @@ Architecture: all
 Depends:
  bsd-mailx | mailx,
  bzip2,
+ dbus,
  ethtool,
  exim4,
  glusterfs-client,
@@ -262,6 +263,7 @@ Depends:
  ldap-utils,
  libavcodec-extra,
  libngcp-rating-inew-perl,
+ libpam-systemd,
  linux-headers-amd64,
  linux-image-amd64,
  mariadb-client,
@@ -349,9 +351,11 @@ Architecture: all
 Depends:
  bsd-mailx | mailx,
  bzip2,
+ dbus,
  iptables-persistent,
  kannel,
  libavcodec-extra,
+ libpam-systemd,
  mariadb-client,
  mariadb-server,
  mytop | mariadb-client-10.1,
@@ -423,6 +427,7 @@ Architecture: all
 Depends:
  bsd-mailx | mailx,
  bzip2,
+ dbus,
  ethtool,
  exim4,
  glusterfs-client,
@@ -435,6 +440,7 @@ Depends:
  ldap-utils,
  libavcodec-extra,
  libngcp-rating-inew-perl,
+ libpam-systemd,
  linux-headers-amd64,
  linux-image-amd64,
  mariadb-client,