install grinder should support install of JBDS from installer, not just BYOE on Eclipse

Max, in JBDS-3485, said:

"I believe the tests all use BYOE install onto JavaEE, not JBDS installer. " that seems very unfortunate and weird since install grinder was written using JBDS to start with.

Can you please make sure we got tests that covers this so we can catch missing pieces like this faster in future ? Thanks.

The install grinder tests [1] run two groovy scripts [2].

[1] http://jenkins.mw.lab.eng.bos.redhat.com/hudson/job/jbosstools-install-grinder.install-tests.matrix_master/
[2] https://github.com/jbosstools/jbosstools-install-grinder/tree/master/scripts/src/main/groovy

One fetches and installs Eclipse; the other performs an installation from an update site or discovery site's directory.xml file.

In neither case is there support for installing JBDS (instead of Eclipse) and performing installations upon that base.

We should add support for that.