[1.3] Fix Ubuntu kontena-server/kontena-agent packages to be incompatible with docker 17.06

[SpComb]

Fixes #2588 for 1.3.x (see #2589 for 1.4)

Installing the kontena-agent 1.3.x package with docker-ce 17.06 installed will now fail:

dpkg: dependency problems prevent configuration of kontena-agent:
 kontena-agent depends on docker-engine (>= 1.10) | docker.io (>= 1.11) | docker-ce (<< 17.06) | docker-ee (<< 17.06); however:
  Package docker-engine is not installed.
  Package docker.io is not installed.
  Version of docker-ce on system is 17.06.0~ce-0~ubuntu.
  Package docker-ee is not installed.

dpkg: error processing package kontena-agent (--install):
 dependency problems - leaving unconfigured

With the new kontena-agent package installed, apt upgrade will hold docker-ce back:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
  cloud-init docker-ce
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.

Although the way it resolves the dependencies when you try and force an upgrade (apt install docker-ce) is odd, it wants to replace the docker-ce 17.03.* package with the older distro docker.io package:

Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 docker-ce : Conflicts: docker.io but 1.12.6-0ubuntu1~16.04.1 is to be installed
E: Unable to correct problems, you have held broken packages.

This shows up in a apt dist-upgrade:

apt dist-upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following package was automatically installed and is no longer required:
  libltdl7
Use 'apt autoremove' to remove it.
The following packages will be REMOVED:
  docker-ce
The following NEW packages will be installed:
  bridge-utils containerd docker.io runc ubuntu-fan
The following packages have been kept back:
  cloud-init
0 upgraded, 5 newly installed, 1 to remove and 1 not upgraded.
Need to get 16.4 MB of archives.
After this operation, 5512 kB disk space will be freed.
Do you want to continue? [Y/n]

[jakolehm]

What about trusty?

[SpComb]

BTW Looks like the resolvconf accidentially slipped in here in #1173, it's not actually needed on the server...

[SpComb]

Tested that upgrading from this 1.3.4 -> 1.4.0 also allows upgrading Docker:

# dpkg -i kontena-dist/deb/kontena-agent_1.4.0.dev1-1_all.deb 
(Reading database ... 82890 files and directories currently installed.)
Preparing to unpack .../kontena-agent_1.4.0.dev1-1_all.deb ...
Deleting resolvconf lo.kontena-docker
Removed symlink /etc/systemd/system/multi-user.target.wants/kontena-agent.service.
Unpacking kontena-agent (1.4.0.dev1-1) over (1.3.4.dev1-1) ...
Setting up kontena-agent (1.4.0.dev1-1) ...
locale: Cannot set LC_ALL to default locale: No such file or directory
disabled
Created symlink from /etc/systemd/system/multi-user.target.wants/kontena-agent.service to /lib/systemd/system/kontena-agent.service.

# apt upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
  cloud-init
The following packages will be upgraded:
  docker-ce
1 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B/20.5 MB of archives.
After this operation, 7183 kB of additional disk space will be used.
Do you want to continue? [Y/n] 
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LC_TIME = "fi_FI.UTF-8",
	LC_MONETARY = "fi_FI.UTF-8",
	LC_ADDRESS = "fi_FI.UTF-8",
	LC_TELEPHONE = "fi_FI.UTF-8",
	LC_NAME = "fi_FI.UTF-8",
	LC_MEASUREMENT = "fi_FI.UTF-8",
	LC_IDENTIFICATION = "fi_FI.UTF-8",
	LC_NUMERIC = "fi_FI.UTF-8",
	LC_PAPER = "fi_FI.UTF-8",
	LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").
locale: Cannot set LC_ALL to default locale: No such file or directory
(Reading database ... 82890 files and directories currently installed.)
Preparing to unpack .../docker-ce_17.06.0~ce-0~ubuntu_amd64.deb ...
Warning: Stopping docker.service, but it can still be activated by:
  docker.socket
Unpacking docker-ce (17.06.0~ce-0~ubuntu) over (17.03.2~ce-0~ubuntu-xenial) ...
Processing triggers for man-db (2.7.5-1) ...
Processing triggers for systemd (229-4ubuntu17) ...
Processing triggers for ureadahead (0.100.0-19) ...
Setting up docker-ce (17.06.0~ce-0~ubuntu) ...
Installing new version of config file /etc/init.d/docker ...
Processing triggers for systemd (229-4ubuntu17) ...
Processing triggers for ureadahead (0.100.0-19) ...