Merge pull request #5 from jcbrand/master

roster plugin: Nickname support added to the presence subscription request.
Extended presence support in MUC
Merge pull request #7 from thePooh/master

Extended presence support in MUC
Some documentation for XEP-0096 and XEP-0047.

Mentioned in,
https://github.com/metajack/strophejs-plugins/pull/102