INT-3383: Update to Smack 4.0.0

It is no longer necessary to supress Smack path warnings.

Delete custom smack-config.xml, as all it did was disabling
certain (important) SASL mechanisms. Also remove the unit test that
verified this.

Some unit tests mock ChatManager and Chat for no reason, delete
those lines.

XMPPConnection.getHost() and .getPort() are only valid after the
connection got established, due the fact that those information is
often only available after a DNS SRV lookup was performed. Remove the
lines in unit tests that verified their value.

Remove the truststorePath example in documentation, since Smack 4.0 no
longer provides support for providing a custom truststore. Instead
ConnectionConfiguration in Smack 4.0 allows to set a custom SSLContext
(which then again can provide a TrustManager that uses a custom
truststore).