Move ispconfig_install.log inside /usr/local/ispconfig, and separate update.log
I'd like to propose moving this logfile into the /var/log/ispconfig/ dir, and store logs from ispconfig updates in e.g. update.log
That would keep the contents of /var/log/ a bit more organized.
And when using TAB-completion the /var/log/ispconfig_install.log file adds an extra step to access the /var/log/ispconfig/ directory.
I don't think we should move previous ispconfig_install.log files. I personally have an Ansible task that moves ispconfig_install.log, but it returns on every update.