set app as owner of log folder in install/restore/update script

[xoddark]

This fix problem of writing log from php actualize_script runed by cron. Issue #148

Problem

• Description of why you made this PR

Solution

• Set app user as owner of app log folder

PR Status

• [X] Code finished and ready to be reviewed/tested
• [ ] The fix/enhancement were manually tested (if applicable) I have tested the manual change of the owner was tested on server, but not the change of the install/restore/update script.

Automatic tests

Automatic tests can be triggered on https://ci-apps-dev.yunohost.org/ after creating the PR, by commenting "!testme", "!gogogadgetoci" or "By the power of systemd, I invoke The Great App CI to test this Pull Request!". (N.B. : for this to work you need to be a member of the Yunohost-Apps organization)

[plopoyop]

!testme

[yunohost-bot]

:v:

[plopoyop]

Install fail :

153734 ERROR Unable to install freshrss: An error occurred inside the app installation script ```

You must remove spaces when affecting defining variable in bash.
You should try to manually install the package to tests you changes

[plopoyop]

I updated my comments (bad copy paste)

[plopoyop]

!testme

[yunohost-bot]

Meow :cat2:

[xoddark]

@plopoyop : thank you for your feedback. I do this PR rapidly, as a start for a fix ;)

[plopoyop]

All ok. Thanks for your contribution :)