Fix XHTMLText.appendBrTag()

It's an empty element and not a closing one.
Use jxmpp 0.2.0

this also changes jxmpp's group from org.jivesoftware.jxmpp to org.jxmpp
Use single threaded ExecutorService

for PacketListeners. Fixes SMACK-583.
Merge branch '4.0'

Conflicts:
	smack-core/src/main/java/org/jivesoftware/smack/XMPPConnection.java
Cleanup carbons, forwarded and a few others API

Adopt to common design patterns in Smack:

- getFrom(Packet) in Packetextensions
- INSTANCES.put() in getInstanceFor()
- ELEMENT instead of ELEMENT_NAME
- Use XmlStringBuilder
Move "Message Events (XEP-22)" code to legacy

Fixes SMACK-569
DRAFT/WIP Abstract SASL Authentication
Add smack-android
Build against android.jar. Thanks to Daryl Tea

for the support implementing this.
Add AndroidDebugger
Added comment
Add getDatestamp
Fix smack-experimental experimental.xml resource
Fix ExperimentalInitializer
Add SmackAndOsgiInitializer

OSGi ServiceComponents need the activate method, make sure it exists for
every SmackInitializer by using this class.
Add getDatestamp() to build.gradle
Smack 4.0.1
Smack 4.0.2-SNAPSHOT
Merge branch '4.0'

Conflicts:
	build.gradle
Merge branch 'master' into sasl

Conflicts:
	build.gradle