feat(engine, api, webapp, static): allow unsecure connections for upload new media ISOs
requested to merge acarfer940/isardvdi:675-add-configuration-to-allow-unsecure-connections-adding-media into devel
According the feature #675 requested here, new variable ENGINE_ALLOW_UNSECURED_CONNECTIONS was introduced in the "engine" section on isardvdi.cfg config file to allow unsecured connections (http instead force use https) to upload media from local servers (e.g: python3 -m http.server) without too much restrictions. This new variable has impact in few places; not only engine, also VueJS frontend, Flask frontend and API to validate request.