Initial KnpMenuBundle integration

> Story: [EZP-22601](https://jira.ez.no/browse/EZP-22601)
> Status: WIP

Integrates a totally non-configurable two level navigation menu, similar to that of ezdemo, to the DemoBundle. Clearly needs to be rewritten,  but it has the basics.

![knpmenu1 pnhg](https://cloud.githubusercontent.com/assets/235928/3598609/77b60f90-0ce5-11e4-97cb-737f384f6c3f.PNG)

What if we just have the following here:
```
# Change branch name ("master") or repository if you need something else to test your PR:
- git clone --depth 1 --single-branch --branch master https://github.com/ezsystems/ezpublish-community.git
- cd ezpublish-community
# If you just need to pull in a different version of one of the dependecies
#- composer require --no-update ezsystems/ezpublish-kernel:dev-my_branch_name
```