Merge pull request #1680 from elakito/atmosphere-2.1.x

remove unused atmosphere-version property
Implementation of "Async Support" for WebSocket transport and Long-Polling fallback to use on JBoss EAP 6.2 with JBoss Native Connector

Implementation of "Async Support" for WebSocket transport and
Long-Polling fallback to use on JBoss EAP 6.2 with JBoss Native
Connector.

This is a approach to solve fix issue
https://github.com/Atmosphere/atmosphere/issues/1670.

It's necessary configuring "init-param" for "AtmosphereServlet" in the
web.xml for use this async support:

<init-param>
<param-name>org.atmosphere.cpr.asyncSupport</param-name>

<param-value>org.atmosphere.container.JBossAsyncSupportWithWebSocket</param-value>
</init-param>
JBossAsyncSupportWithWebSocket autodetect

Change on DefaultAsyncSupportResolver for Atmosphere to autodetect
JBossAsyncSupportWithWebSocket
Announce 2.2.0 in next release
Proper
Fixes #1673
Improve Fixes #1673: clear all states
Improve Fixes #1673: clear all states
Port 72981206ab83a9c2d861c2d22fe25b6b354245a5
Port 72981206ab83a9c2d861c2d22fe25b6b354245a5
[maven-release-plugin] prepare release atmosphere-project-2.1.8
[maven-release-plugin] prepare for next development iteration
Fixes #1690
First pass for #1692

Make it possible to configure a default Serializer and use it in AtmosphereResourceFactory.
Fixes #1539, workaround #1706
Use new tag
[maven-release-plugin] prepare release atmosphere-project-2.1.9
[maven-release-plugin] prepare for next development iteration
Fixes #1735
Backport #1734