This should make investigation of errors on testnode easiers, any logged
messages by test framework goes to testcase.log

Setup logging at the very beginning, to also have messages logged during
initialization

Also adjust a bit the logged messages, we don't need to log everytime we
snapshot a file or folder, this cause the log to be very big, but it can
be interesting to log when we start and stop checking software, so that
we see how long this took.

On test nodes, these socket path sometimes exceed the linux limit.

Once testnodes are updated and always set SLAPOS_TEST_LOG_DIRECTORY, we
no longer need to have a default case of creating a snapshot folder
automatically, which was causing difficulties when running tests locally
as we had to remove this folder manually between test executions.

When this test fail we had incorrect traceback

   When a Hosting Subscription is destroyed, the related Subscription Request is stopped.

   This can prevent a useless message be pushed to the user.

   By replacing the templates, the site must indeed continue to work as usual, and the new organisation should take place of organisation_module/slapos

     Create methods to replace the templates on preferences by their clones with small modifications.

    The goal is allow us to ensure that the values on the templates aren't harcoded on other locations, making it impossible to reconfigure the site.

   Move definition into preferences

    Merged into SystemPreference_viewSlapOS Form

    The source was changes to be same as source_section

See merge request nexedi/slapos.core!222

See merge request nexedi/slapos.core!240

This reverts commit 7e49ec5e.

This reverts commit febcf1b4.

See merge request nexedi/slapos.core!239

See merge request nexedi/slapos.core!185

See merge request nexedi/slapos.core!236