Fortinet SSLVPN support for NetworkManager

This requires the openfortivpn client installed, version 1.10 or newer.
https://github.com/adrienverge/openfortivpn

(C) 2015 - 2019 Lubomir Rintel <lkundrak@v3.sk>

Based entirely on PPTP support:

0.7.x version:
(C) 2008 Dan Williams <dcbw@redhat.com>, and Tambet Ingo <tambet@gmail.com>

0.6.x version:
(C) 2005 - 2007 Antony Mee   http://www.students.ncl.ac.uk/a.j.mee
Based entirely on OpenVPN support by Tim Niemueller http://www.niemueller.de