add revision_type to revisions in endpoints

tracim/models/context_models.py

         return self.revision.label
 
     @property
+    def revision_type(self) -> str:
+        return self.revision.revision_type
+
+    @property
     def content_type(self) -> str:
         content_type = ContentType(self.revision.type)
         if content_type:

tracim/tests/functional/test_contents.py

         assert revision['status'] == 'open'
         assert revision['workspace_id'] == 2
         assert revision['revision_id'] == 6
+        assert revision['revision_type'] == 'creation'
         assert revision['sub_content_types']
         # TODO - G.M - 2018-06-173 - Test with real comments
         assert revision['comment_ids'] == []
         assert revision['status'] == 'open'
         assert revision['workspace_id'] == 2
         assert revision['revision_id'] == 7
+        assert revision['revision_type'] == 'edition'
         assert revision['sub_content_types']
         # TODO - G.M - 2018-06-173 - Test with real comments
         assert revision['comment_ids'] == []
         assert revision['status'] == 'open'
         assert revision['workspace_id'] == 2
         assert revision['revision_id'] == 27
+        assert revision['revision_type'] == 'edition'
         assert revision['sub_content_types']
         # TODO - G.M - 2018-06-173 - Test with real comments
         assert revision['comment_ids'] == []
         assert revision['workspace_id'] == 2
         assert revision['revision_id'] == 8
         assert revision['sub_content_types']
+        assert revision['revision_type'] == 'creation'
         assert revision['comment_ids'] == [18, 19, 20]
         # TODO - G.M - 2018-06-173 - check date format
         assert revision['created']
         assert revision['status'] == 'open'
         assert revision['workspace_id'] == 2
         assert revision['revision_id'] == 26
+        assert revision['revision_type'] == 'edition'
         assert revision['sub_content_types']
         assert revision['comment_ids'] == []
         # TODO - G.M - 2018-06-173 - check date format

tracim/views/core_api/schemas.py

 from tracim.models.context_models import WorkspaceAndContentPath
 from tracim.models.context_models import ContentFilter
 from tracim.models.context_models import LoginCredentials
-from tracim.models.data import UserRoleInWorkspace
+from tracim.models.data import UserRoleInWorkspace, ActionDescription
 
 
 class UserDigestSchema(marshmallow.Schema):
         example=12,
         validate=Range(min=1, error="Value must be greater than 0"),
     )
+    revision_type = marshmallow.fields.String(
+        example=ActionDescription.CREATION,
+        validate=OneOf(ActionDescription.allowed_values()),
+    )
     created = marshmallow.fields.DateTime(
         format=DATETIME_FORMAT,
         description='Content creation date',