[OXUI-585] remove nodejs build dependency on OBS

We currently support a few Linux distributions only shipping very old versions of nodejs. Since gruntjs recently dropped support for node 0.10 and 0.12, we can not update our build stack any longer. The idea now would be to just drop the dependency on nodejs during package build time and switch to a version where we just copy around ready built files on the target systems. All the heavy lifting will be done in the normal build pipeline, because we need built sources anyway for running all the tests and deploying preview apps, …

See OXUI-585 for details.