SPARK-2338 Refactor: rename the confusing "Old SSL" to "Direct TLS"

[stokito]

The code uses a term "Old SSL" for Direct TLS connections on port 5223.
This is supported by XEP-0368 and may be not necessary for old clients.
To make the code follow same terminology as XEP I renamed the LocalPreferences.isSSL() to isDirectTls(). The property name in properties file internally remains same.

Additionally extract the similar code to configure TLS in the Login and AccountCreationWizard.

[stokito]

Check the comment:

 SMACK 4.1.9 does not support XEP-0368, and does not apply a port change, if the host is not changed too.
 Here, we force the host to be set (by doing a DNS lookup), and force the port to 5223 (which is the default 'old-style' SSL port).

It looks like this Direct TLS code should be moved into the Smack library. Probably to this place https://github.com/igniterealtime/Smack/blob/4aacdc5154e7eb55df175bf661abbb627f6f76a7/smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XmppTcpTransportModule.java#L626

[Plyha]

As I understand it, Direct TLS is depricated, I don't think it will be added to Smack, but it's worth telling @Flowdalic about it

[stokito]

from the XEP:

It also provides an easy way for clients to bypass restrictive firewalls that only allow HTTPS, for servers to host multiple protocols/services on a single port, and for servers and clients to take advantage of less round trips and existing direct TLS loadbalancers.

So it's useful and basically can be even better.

Also please check the last commit 6ee0092. I extracted two methods that looks similar but maybe this should be the same method. It looks like the AccountCreationWizzard is just has an outdated version.