Several tweaks so that it is possible to run bin/test once more (one
of the tests still fails):

- Django-haystack 2.0 requires a HAYSTACK_CONNECTIONS setting
- Moved a ddsc_api import into a view, so that only that view depends
  on ddsc_api and we don't have to require it just for running tests.
  The view (views.VersionView) should probably be moved to ddsc_api.
- Add ddsc_core to requirements, as we use things from it.
- Update Django version in Buildout to 1.5.5, because lizard-auth-client
  needs that, and DDSC is moving to that version anyway.
Use Django 1.5.4

DDSC-API had trouble depending on 1.5.5, so use 1.5.4 here as well.
Merge pull request #11 from ddsc/remco-getting-tests-to-run

Several tweaks so that it is possible to run bin/test once more (one