Add RBAC support to navigation helper.
Add trigger to 'accept' method. Remove previous changes.
Amend method documentation.
Implementing and re-utilizing an abstract aggregate listener

as of zendframework/zf2#3874
Merged Source/Master
Refactored ACL. Fixed tests.
Merge pull request #3693 from francisdaigle/develop

[WIP] Add RBAC support for navigation helper.
[#3693] CS fixes

- Docblock additions/edits
- Logic workflow
[#3693] CS fixes

- trailing whitespace
- EOF endings
Reverting the naming from 'callbacks' to 'listeners' for callback handlers in aggregates
Merge pull request #3876 from Ocramius/feature/abstract-aggregate-listener

Implementing and re-utilizing an abstract aggregate listener