Docs : upgrade paths

Independently from installing a bare system, it is often advised to upgrade the modular components of modoboa as suggested via the /core/#info/ route of the web interface.

module	pip package
Modoboa	modoboa
Amavis	modoboa-amavis
PDF credentials	modoboa-pdfcredentials
Postfix autoreply	modoboa-postfix-autoreply
Sieve filters	modoboa-sievefilters
Statistics	modoboa-stats
Webmail	modoboa-webmail

These packages are upgraded within the modoboa virtual environment before reissuing the installer script. If, for example, a new modoboa version has been published on PyPi and a newer, unpublished version exists already in some soure control, one could do the following:

# . /srv/modoboa/env/bin/activate
(env)# pip install --upgrade modoboa
(env)# pip install https://github.com/modoboa/modoboa-pdfcredentials/archive/master.zip --upgrade
(env)# deactivate

Then a redeployment happens with

# ./run.py email.ecobytes.net --debug

One could even use different installer.cfgs to not reconfigure amavis, clamav, dovecot, nginx, razor, postfix, spamassassin and uswgi at all times. These could be loaded by parsing the provided FQDN of an instance and mapping it to distinct FQDN.cfg while an --upgrade switch omits the reconfiguration of the additional services.

[spinza]

The upgrade process is not clear. That to me is the main issue. It is not clear how to upgrade.

[almereyda]

Upgrade notes now live in http://modoboa.readthedocs.io/en/latest/upgrade.html

The notes in http://modoboa.readthedocs.io/en/latest/upgrade.html#extensions also apply

> sudo -i <modoboa_user>
> source <virtuenv_path>/bin/activate
> pip install <EXTENSION>==<VERSION>
> cd <modoboa_instance_dir>
> python manage.py migrate
> python manage.py collectstatic
> python manage.py check --deploy