SPARK-1989 create empty KeyStores

[Alameyo]

New empty KeyStores are created each time when user open advanced panel and there are no existing KeyStores in user directory already.

[wrooot]

What does it mean that user opens advanced panel? What if a user doesn't ever open it and just hits login on a fresh profile?

[Alameyo]

Then KeyStores are opened if exist, if not new empty KeyStores are created because TrustManagers/KeyManager need them but I don't save them. Anyway if there were no KeyStores then user shouldn't be able to connect until he add required certificates (and by that open advanced panel).
For next PR I am working on adding Java cacerts file so user will be able to connect with some default certificates.

[wrooot]

The usual user-friendly model is that if an unknown/self-signed certificate is encountered, the app provides a dialog/popup with an immediate option to add this certificate to an exception list or do a one time login. A number of clients i have used do this, browsers do this. It can involve a few steps, but a user shouldn't be looking for a menu to add a certificate to exceptions. A list of default certificates won't solve this.

[Alameyo]

I agree, that is thing I should to add. I will work on that.

[guusdk]

There's a lot of boilerplate code here. There are fragments of code, that are pretty much duplicates, but use different variables. Let's replace those with a method.

[guusdk]

The popup is certainly desirable, but not part of the GSoC project. Let's focus on finishing that first. We'll create the pop-up directly afterwards.

[guusdk]

Thanks :)