* remove invite_conference_update media file, this has to be a link
* ngcpcfg apply executed outside /etc/ngcp-config seems to generate
.ngcpcfg_perms file in $pwd so adding a workaround to avoid it
* bench.sh: support selecting the GROUP scenario
* show_flow_diff.pl: improve the diff output adding the values of
the flows not only the names
Change-Id: I40db8433595168ce8d3ef061f77f02a1616ed980