Update Smack to 4.0.5

The Smack version openhab currently uses contains security vulnerabilities. This PR updates Smack to the latest stable version.

For the record: While preparing the commit I found some issues with the current XMPP openhab action:
- It does not use DNS SRV records to resolve the XMPP server
- It does not allow TLS

If I find the time, I may address those issues with future commits.

And since Smack is on maven central, and becomes more and more modular (see the upcoming Smack 4.1 version), it would be great if I could add maven dependencies instead of binaries. Will this ever be supported by openhab? Maybe with openhab2?