Added tutorial on advanced configuration

- Covers all the various ways to manipulate configuration, including the order in which
  configuration is merged.
- Added information on the configMerge event to the module manager chapter, linking it to the
  tutorial.
Incorporate feedback

- from @superdweebie
Merge branch 'feature/config-tutorial' into feature/zf2-4505

Bring in changes from #904

Conflicts:
	docs/languages/en/tutorials/config.advanced.rst
Merge branch 'feature/zf2-4505' of https://github.com/weierophinney/zf2-documentation into hotfix/#882
Merge branch 'hotfix/#882' into develop

Close #882