INT-3383: Update to Smack 4.0.0

Remove the unneeded dependency to smackx (which is now the
smack-extensions artifact). If users need functionality out of
smack-extensions (typically some XEP related one) they have to add the
dependency themselves. Note that there is also smack-experimental for
experimental and draft status XEP code.

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).
Well, I see there is an issue with new Smack and old Spring WS.
Is Smack 4.0 compatible with a Smack 3.0? I mean can we have in the classpath both versions? 
I'm not sure how quickly the Spring WS (2.3.0) with new Smack will be released so we should be carefull with the new Smack for SI and old one for WS, because we can't release our project with a milestone dependency.
Just in case: can we live with both Smacks in the CP?