Werk #7648: Fix fstab appending when file does not end with a newline

When a new site is created an entry for the tmpfs of the site is appended to the /etc/fstab. In case the last entry of the file did not end with a newline character the appending of this tmpfs entry resulted in a broken line.

We now check the previous entry ends with a newline char and ensure it is separated with a newline char correctly.

To the list of all Werks