new installer mechanism

I have documented the new way we plan on being able to install the RHQ Server in a design document here:

https://docs.jboss.org/author/display/RHQ/Installing+RHQ+on+JBossAS+7

The page is rather short and to the point because I wanted to avoid giving too much implementation detail. This only provides the installation steps that should be necessary to install the latest RHQ (this is not yet in master branch - but it will be shortly).

If anyone has any comments, concerns or sees any problems with this approach, post to this thread for discussion.