Add releng component for building with buckminster

This enables mirroring of the p2.site using p2 actions from buckminster
This file also contians extra dependencies needed to build the bundles in this repo
Updates bundle versions to 2.6.1
Feature version set to 2.6.1
Removed the dependency on the cdk.business plugin by using SMILESMolecule (suggested by Arvid)
Merge pull request #2 from egonw/bug/removeCDKBusinessDependency

fix: remove CDK business dependency
Merge branch '2.6.1' into develop