Add json extensions

Add the json suffix (ALL_JSON, similar to ALL_XML) and add the specific Activity Streams (http://activitystrea.ms) json prefix, "application/activity+json".
Released Restlet 2.2RC2
Fixed issue #818: Call.isBroken does not detect Tomcat ClientAbortException. Reported and contributed by Jeremy Gustie.
Fixed issue #818: Call.isBroken does not detect Tomcat ClientAbortException. Reported and contributed by Jeremy Gustie.
Add JSON media types. Reported and contributed by mafuba.
Merge pull request #840 from mafuba/patch-1

Add JSON media types. Reported and contributed by mafuba.
Fixed documentation.
Merge branch 'master' of github.com:restlet/restlet-framework-java
Addd checking of maven library configuration - updated some maven configuration.
Fixed issue #836, regarding maven check.
DELETE responses send 200 status without any entity, whereas it should be 204.
DELETE responses send 200 status without any entity, whereas it should be 204, issue #847.
Updated scala library.
      - Moved all the remaining NIO logic from previous internal HTTP connector to the
        org.restlet.ext.nio. This will help reduce the org.restlet.jar file size.
      - Issue #805: The NioUtils.copy(..) logic that sometimes created Cyclic barrier
        exceptions has been moved as well and replaced with the older and more stable
        logic that was in place in version 2.1.0 and older releases.
        Reported by Wim Jongman.
      - Issue #805: The NioUtils.copy(..) logic that sometimes created Cyclic barrier
        exceptions has been moved as well and replaced with the older and more stable
        logic that was in place in version 2.1.0 and older releases.
        Reported by Wim Jongman.
 - Cleanup uneeded Javadoc overview templates.
Updated documentation.
Released Restlet 2.2rc3.
Released Restlet 2.2rc3.
Fixed gwt edition.
Released Restlet 2.2rc3