Release slixmpp 1.4.0

Important changes:
- Dropped python 3.4 compatibility (async/await syntax)
- Fixed Python 3.7 compatibility
- Improved examples
- Many bugfixes

Thanks to all contributors!

slixmpp 1.3.0

- Add a Markup (XEP-0394) plugin
- Add a Hashes (XEP-0300) plugin
- Update (and fix) MAM (XEP-0313) for mam:2
- Fix RSM
- Fix (or at least improve) and egregious connection issue
- Various fixes and improvements

1.2.4 release

slixmpp 1.2.3, to fix tests

slixmpp 1.2.2 release to fix CVE-2015-8688

slixmpp 1.2.1 release

Fixes a few bugs and the testsuite, and remove the asyncio event loop
monkeypatching hack.

slixmpp 1.2 release (02-10-2016)

SleekXMPP v1.1.10

SleekXMPP v1.1.10