[bug] Reverting template from history doesn't send config changed signal

[nemesifier]

Steps to replicate:

• Create a template, save, then do some minor changes
• Assign the template to a device, save
• From the history (django-reversion), revert the template to the previous save point

Expected outcome: device config status becomes modified and config updates
Actual outcome: device config status does not change

This may be happening also when reverting the device to a previous state, we shall find out.