vifib-server += nxd-fuse on Debian 9, Debian 10, Ubuntu 16.04

nxd-fuse is fuse package from those distribution with backported
git.kernel.org/linus/ad2ba64dd489 for wendelin.core 2 to be able to
fully and explicitly control OS pagecache for files that wcfs serves.
This patch is very essential for wendelin.core 2.

The sources for nxd-fuse package are located in fs/fuse/ here:

https://lab.nexedi.com/kirr/linux/commits/nxd/fuse/debian/buster	(Debian 10)
https://lab.nexedi.com/kirr/linux/commits/nxd/fuse/debian/stretch	(Debian 9)
https://lab.nexedi.com/kirr/linux/commits/nxd/fuse/ubuntu/xenial	(Ubuntu 16.04)

I tested the package by myself for a long time on my Debian10-based
laptop via go-fuse tests and while working on wendelin.core. Ubuntu
package was also tested for a long time on my KVM via manually running
the same tests and, recently, via running wendelin.core 2 tests on
testnode located on the same KVM. I tested Debian 9 module only briefly
on my Debian 9 KVM, but given that the diff in between nxd-fuse and
std/ fs/fuse/ for that kernel is essentially only
git.kernel.org/linus/ad2ba64dd489, and that the debianisation was
already tested well via Debian10, and that go-fuse and wendelin.core 2
tests pass, it should be ok.

The packages are built on OBS here:

https://build.opensuse.org/package/show/home:VIFIBnexedi/nxd-fuse
https://build.opensuse.org/package/view_file/home:VIFIBnexedi/nxd-fuse/README

I've used vifib-kernel role as the place where to add corresponding
play. Nxd-fuse is tightly related to kernel and requires reboot after
installation, which, if I understood correctly, needs infrastructure
internal to that role to work correctly.

/cc @rafael, @tomo, @vpelletier

playbook/roles/vifib-kernel/tasks/main.yml

@@ -35,6 +35,16 @@
     when: ansible_distribution == "Debian" and ansible_distribution_major_version == "7"
     notify: [ 'Mark to reboot' ]
 
+
+  # install nxd-fuse on old Debian and Ubuntu
+  - name: Install nxd-fuse
+    apt: name=nxd-fuse-dkms state=latest update_cache=yes
+    when: (ansible_distribution == "Debian" and ansible_distribution_major_version == "10") or
+          (ansible_distribution == "Debian" and ansible_distribution_major_version == "9")  or
+          (ansible_distribution == "Ubuntu" and ansible_distribution_version == "16.04")
+    notify: [ 'Mark to reboot' ]
+
+
   - name: create trigger reboot script
     copy: src=slapos-trigger-reboot.sh dest=/usr/local/bin/slapos-trigger-reboot.sh mode=700