ESC-13 Add Artifact extension which deals with artifact resolution

* It also deals with artifact attachment to deployments (i.e. Lift jars)
* This new extension will be reused by other extensions.
* Restructured entire Arquillian testsuite to be stored in each module
and be executed via the Maven Invoker plugin. This makes it easier for
the future when you wanna test the same code with different Scala
versions.
ESC-13 Use embedded container for testing

* Define pluginManagement section to centralize configuration of
Maven plugins.
ESC-13 Split assembly to separate project to reduce dist dependencies

* Update Version information.
* Update roadmap.
ESC-13 Add extension and subsystem XML fragments programmatically

* Makes it easier to deal with changes to underlying AS standalone
configuration.
* Update root README file with new structure.
ESC-13 Provide TRACE logging for io.escalante in testing
ESC-13 Remove build/ project and unzip base app server from code

* Use same code to unzip base app server when building distribution.
* Adjust arquillian listeners to that they unzip the base server
before test set up if necessary.