Firefox prompt to ask for "Yes / No"

[guybedford]

Instead of assuming the Firefox check, we could change this to "Would you like to install the certificate in Firefox? [Yes/No]: ".

Ideally we could auto-detect if Firefox is even installed on the system, and not show the above at all on systems that definitely don't have it.

[jimthedev]

I actually haven't had much luck getting the FF 59.0b5 functionality working (I've done minimal digging). In the end I have just dumped the CA certs to the file system and then drag and dropped them in. If this is the case then maybe the best bet is to even offer the ability to just shut this off.