I added the following prefs to my user-overrides.js file:
The first determines whether to use security certificates provided by the OS. This apparently works for Windows and Mac but i'm unsure whether it applies to Linux. Nevertheless i added it anyway.
The latter re-enables TLS 1.0 and 1.1 support. If this is disabled then websites that use older TLS protocols, such as some personal sites which are not maintained, yet might have great information, will not load by default. If you set this to 'false' you will be given the option to enable it when Firefox runs into a site that uses the older protocols, so if you don't like this change then just copy the pref to the user section and set it to 'false'.
You can grab the file here.