Revert "implement before/after to declare dependencies and deprecate require"

Comment from asteven:
    Some problems showed up while updating the docs and tests.
    You should revert the merge for now.

This reverts commit 84770b9ef2.

cdist/test/object/__init__.py

@@ -87,7 +87,6 @@ class ObjectTestCase(test.CdistTestCase):
         self.cdist_object.code_local = ''
         self.cdist_object.code_remote = ''
         self.cdist_object.state = ''
-        self.cdist_object.requirements = []
 
     def test_name(self):
         self.assertEqual(self.cdist_object.name, '__third/moon')