Security enhancement for the JTOpen library

[MarcelRomijn]

Added a security enhancement that allows setting a custom SSLSocketFactory for making secure connections to a host.
This enhancement is available for both JTOpen connections made with the SecureAS400 class and with the AS400JDBCDriver class.

I created another GitHub repository that contains tester code to test/demonstrate the security enhancement (in branch feature/security): https://github.com/MarcelRomijn/JTOpen_security_test/tree/feature/security

[nadiramra]

Not sure we will be going this way. I think our thought is giving users the ability to specify path to certificate store with a password, and the additional option to indicate whether or not all certificates should be trusted (in which case no certificate store needs to be specified).

[MarcelRomijn]

@nadiramra, only specifying a path to a certificate store with a password will not work for us.
We use JTOpen in a server environment where a configuration is dynamically set. Through that configuration, a collection of trusted certificates are obtained. At runtime, an SSLSocketFactory is built, which is then handed over to JTOpen.

One option could be to implement both:

1. The current implementation in the PR, which allows for maximum flexibility by dynamically creating an instance of `SSLSocketFactory'.
2. An extra API, where the path to a certificate store with password can be provided. And maybe also a variant where an instance of KeyStore can be provided in case the user has already read it.

Obviously, that second extra API can make use of the first one.

[trknz]

Not sure we will be going this way. I think our thought is giving users the ability to specify path to certificate store with a password, and the additional option to indicate whether or not all certificates should be trusted (in which case no certificate store needs to be specified).

@nadiramra, could you provide an estimated timeframe? Even a rough indication would be helpful.