Update OpenShift cartridge to latest SimplePush and UnifiedPush Servers

The configuration for the SimplePush server has changed and the Netty Subsystem has now been removed and the code moved into the SimplePush servers git repo (wildfly module).

While doing this we also made minor updates to the configuration in standalone.xml:
The name of the extension has changed to:

<extension module="org.jboss.aerogear.simplepush"/>

The subsystem configuration has changed to:

<subsystem xmlns="urn:org.jboss.aerogear.simplepush:1.0">
  <server name="simplepush-server" socket-binding="simplepush" factory-class="org.jboss.aerogear.simplepush.subsystem.SimplePushBootstrapFactory" datasource-jndi-name="java:jboss/datasources/SimplePushDS" token-key="838c==27dd2221AB37" endpoint-tls="true"/>
</subsystem>

Note that the endpoint-tls options is new and will be available when AGPUSH-279 is merged. Later all configuration will be done this way but we added this one so that we don't later have to rebuild simplepush to switch between http/https for the notification endpoint urls.
Also note that the package name for the SimplePushBootstrapFactory has changed so just adding endpoint-tls for example will lead to a failure upon startup.

In the cartridge itself only the org.jboss.aerogear.simplepush module is required and org.jboss.aerogear.netty can be deleted.
I've been updating this branch during testing and might good as a reference.