PubSub protocol support (#142)

* PubSub protocol support
Added support for :
- XEP-0050   (Command))
- XEP-0060   (PubSub)
- XEP-0004   (Forms)

Fixed the NewClient function by adding parsing of the domain from the JID if no domain is provided in transport config.
Updated xmpp_jukebox example

* Delete useless pubsub errors

* README.md update
Fixed import in echo example

* Typo

* Fixed raw send on client example

* Fixed jukebox example and added a README.md

stanza/pep.go

@@ -15,7 +15,7 @@ type Tune struct {
 	Uri     string   `xml:"uri,omitempty"`
 }
 
-// Mood defines deta model for XEP-0107 - User Mood
+// Mood defines data model for XEP-0107 - User Mood
 // See: https://xmpp.org/extensions/xep-0107.html
 type Mood struct {
 	MsgExtension          // Mood can be added as a message extension