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.


@rafabene @psiroky That version (6.2.0-SNAPSHOT) will resolve correctly if the jboss nexus community maven repo is included in A) either your settings.xml or in B) the pom.xml itself.
All of kie's projects use approach B) so newbie contributors don't have to jump through any hoops.