We have fortigate but fortios is the newer version: http://www.fortinet.com/press_releases/121016_os5.html
Separated fortios out now, using the newer sysObjectId for detection including serial number support.
Files all have separate commits showing where the MIB and images are from.
I've added an Appliance device type as these don't fall into existing types imho. Can be changed if people disagree.
Added FortiOS definitions + appliance type
Added appliance logo - this is a copy of apps.png
Added basic detection for FortiOS
Auto-Deploy finished, Test PR at http://1815.ci.librenms.org or https://1815.ci.librenms.org