BOMs refactoring

Please DON'T MERGE THIS YET. It is still work in progress, but I want to get early feedback from others, so that's why I am creating this PR.

We discussed some of the changes with @ge0ffrey @rafabene and @pmuir in past few weeks. With @ge0ffrey  we decided _not_ to move the BOMs to community repositories as they should only be released when product is actually released. We will still create a CI job that will locally build the BOMs and quickstarts and will sure they work as expected.

The following changes should be done as part of the refactor:
* introducing `brms-bmpsuite-bom-parent` that will contain the shared info like version properties, etc
* added `jboss-brms-bpmsuite-bom` that contains only the drools/jbpm/optaplanner artifacts (no javaee stuff)
* refactored the `jboss-javaee-6.0-with-drools` into `jboss-javaee-6.0-with-brms-bpmsuite` as it already listed more than just Drools artifacts.


Yes, currently there are product artifacts specified there. I am still not sure about the best approach here. I could either revert to 3.0.2.Final which is hopefully publicly available and then this one would be overwritten during the product build. However, I wanted to make the poms as close to the product version as possible so that we can have a higher confidence that the BOMs will be OK for the product build. Also if we will tag the BOMs repo (and we should) we will need to have the product versions there. E.g. for tag 6.1.0.CR1 the kie.version would be something 6.2.0.Final-redhat-3