Optimize Generic Setup dependency graph

I've optimized the Generic Setup dependency graph.

## Aim
The primary aim is to increase development speed and pleasure by reducing the time it takes for running a single test. It also affects the total test time but it is not that noticeable when running all tests which takes much longer.

## Timing
I've timed the ``opengever.core.testing.OpengeverFixture.installOpengeverProfiles`` method, which installs the opengever generic setup profiles.

### OpengeverFixture.installOpengeverProfiles
Current base (master): ``20007.419825 ms``
Current HEAD (jone-tests): ``12306.541920 ms``
Difference:  ``-7700.877905 ms`` (``-38%``)

### Total time running one test
``time ./bin/test -t test_filing_number_fields_is_hidden_in_site_without_filing_number_support``
Current base (master): ``./bin/test -t   32.00s user 3.89s system 99% cpu 35.924 total``
Current HEAD (jone-tests): ``./bin/test -t   24.48s user 3.76s system 99% cpu 28.270 total``

## Graph
The graph is built with all ``metadata.xml``s within the ``opengever`` folder.
External profiles (not within ``opengever``) are colored red because their dependencies are not included.
Siblings are unordered in the graph, however they are ordered in the reality.
Changes were made in each commit to the ``opengever.policy.base`` and ``OpengeverFixture.installOpengeverProfiles`` dependency order concurently.

### Before
![dependencies-before](https://cloud.githubusercontent.com/assets/7469/4323057/6b58b74e-3f4d-11e4-9303-b5ae6f6f8b55.png)

### After
![dependencies-after](https://cloud.githubusercontent.com/assets/7469/4323060/7162af28-3f4d-11e4-9d7a-0bbac100359e.png)

@phgross please take a look :wink: