Fixes#1495
/etc/systemd/system/docker.service was missing the [Install] section
making the enable action fail with:
```
root@jessie:~# systemctl enable docker
Synchronizing state for docker.service with sysvinit using
update-rc.d...
Executing /usr/sbin/update-rc.d docker defaults
Executing /usr/sbin/update-rc.d docker enable
The unit files have no [Install] section. They are not meant to be
enabled
using systemctl.
Possible reasons for having this kind of units are:
1) A unit may be statically enabled by being symlinked from another
unit's
.wants/ or .requires/ directory.
2) A unit's purpose may be to act as a helper for some other unit which
has
a requirement dependency on it.
3) A unit may be started when needed via activation (socket, path,
timer,
D-Bus, udev, scripted systemctl call, ...).
```
Signed-off-by: Emmanuel Bretelle <chantr4@gmail.com>
36ec026b38