Enable use of maven to import external lib jars into XTS

The XTS build process employs a variety of external jars:

JBossTS jars
JBossWS jars (including Java EE API jars, JBossWS native jars and CXF jars)
JBossAS jars (including Java EE API jars)
other java jars (junit)

The build process should normally employ the JBossTS jars produced by building JBossTS in the source tree containing XTS as a subtree. However, in the case of the other sets of jars it should be possible to build XTS with a guarantee that the build employs known versions of each of the required jars.

This should be achieved using maven to resolve dependencies and download the required jars. In the case of the AS and WS jars the versions should be derived from the component-matrix pom associated with a specific version of the AS to which the XTS and TS tree is matched.