Prefer the Liberation fonts over Arial/Times

The new Writer template was supposed to use the Liberation fonts: http://nabble.documentfoundation.org/Default-Writer-Template-td4076271.html
So I changed the defaults to prefer them over their MS equivalents. When they are not available, they will be substituted as used.

This should not cause problems since the Liberation Fonts have the same metrics as Times, Arial and Courier New.

Change-Id: I00dc14db2aee3b6f57eec7b6f93b69fcf8e5c2cc
Reviewed-on: https://gerrit.libreoffice.org/6886
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>