Use defaultLinuxLogsLocation for /var/log

Log directory `logs` in the installation directory is soft-linked to `/var/log/app-name/`. Instead of hard coding `/var/log` use the already provided variable `defaultLinuxLogsLocation`.

I would also offer to add a test and have prepared one in 3f81f5b, but I only know how to check symbolic links using Java 7’s NIO2 and I think you try to keep Java 6 compatibility.