Remove hard-coded paths to AS distribution

There are currently a lot of places in the arquillian and testsuite modules which contain a hard-coded path to the location of the AS distribution (build/target/jbossas). This makes it difficult to change this path when re-branding the AS.
It would be good if these could be configured to use a single POM property such as jboss.home and/or jboss.dist so that the path can be updated in a single place.