Update .deb installation in bootstrap-ansible.sh

Now script can correctly install old and new style .deb packages
generated by 'make deb'. Also shell has been downgraded to /bin/sh and
text of the GPLv2 license has been added to the script.
Fix idempotency issue within 'apt' role

On a normal ginas host with only common roles enabled this bug did not
show up, but it might be present later, when different services are
enabled.

As it turns out (actually, I haven't bothered to check, just a guess),
'apt_repository' module, to ensure that a specified repository is not
present in /etc/apt/sources.list, rewrites the whole file. I'm not sure
why, but a line with one '#' character (creating a better whitespace in
the comment text) is modified by the module during rewrite process to
'# ', ie. with an added space after '#' character.

This innocent rewrite presents a problem on the next run - Ansible
'template' module sees that /etc/apt/sources.list file has been modifed,
and replaces it with a new, correct version (without the space present
in '#' empty line). Which generates a change event. Which then shows up
at the end of the playbook run with usually just 1 change.

And then user might wonder, what changed? The playbook is big, it might
take several minutes to find out what caused the change. And it also
means, that the whole playbook is idempotent, which shouldn't happen.

I pondered for a while if that should be reported as a bug in
'apt_repository' module, after all this is the culprit, not 'template'
module which only does its job. But in the end it's not that important,
because it's just a meaningless empty comment line that is modified.

So I decided to remove that lonely '#' character instead and move on.

/ducks/
                        ___
                      .'   '.__
                     (    o {__)     __  '-.  .'
                      \  ._.'    __.'  '.   '   .-'
               /\      )  (     (__} o   ) .-')    _
              |  ``'"'`    \       '.__. /` .'   .'  '
              \  {`'-       }    (`--')  _.'--`\
            jgs'. '-._     /      `-.{        _ )
           ``^^`^`^`^^`^^`^``^`^````^`^^^`^`^^`^^`^^
Add 'domain' parameter description in mailman role

You can use 'domain' parameter in list of Mailman lists to specify that
a particular list should be available in a different domain than the
default.
Fix typo in Postfix dependency config of Mailman
Add support for HTTPS protocol in APT

'apt' role will now be able to use https:// repositories. apt-cacher-ng
proxy is disabled for HTTPS-based APT repositories (otherwise they are
not accessible).
Support new / old .deb packages in 'ansible' role
Change the type of default variables in dnsmasq

Previously the type of empty variables was defined as a list ([]), now
they will be hashes by default ({}).
Update CHANGELOG.md
Don't display full idempotency test in Travis CI

Travis CI output is cut after 10000 lines, this patch tries to only show
changed tasks during idempotency test to mitigate that problem.
Fix identation in .travis.yml
Merge pull request #105 from drybjed/bugfixes

Various bugfixes and enhancements