Introducing external video encoding

It is now possible to specify an encoding backend (at the moment only
zencoder) to take care of video variations encoding. Files transfer
happens directly on CGS (although any storage backend can be
supported). New requirements is the Zencoder Python library.

pillar/settings.py

@@ -349,20 +349,6 @@ files_schema = {
     'description': {
         'type': 'string',
     },
-    # If the object has a parent, it is a variation of its parent. When querying
-    # for a file we are going to check if the object does NOT have a parent. In
-    # this case we will query for all files with the ObjectID as parent and we
-    # will aggregate them according of the type (if it's an image we will use
-    # some prefix, if it's a video we will combine the contentType and a custom
-    # prefix, such as 720p)
-    'parent': {
-        'type': 'objectid',
-         'data_relation': {
-            'resource': 'files',
-            'field': '_id',
-            'embeddable': True
-         },
-    },
     'content_type': { # MIME type image/png video/mp4
         'type': 'string',
         'required': True,
@@ -459,20 +445,22 @@ files_schema = {
             }
         }
     },
-    'previews': { # Deprecated (see comments above)
-        'type': 'list',
+    'processing': {
+        'type': 'dict',
         'schema': {
-            'type': 'objectid',
-            'data_relation': {
-                'resource': 'files',
-                'field': '_id',
-                'embeddable': True
-            }
+            'job_id': {
+                'type': 'string' # can be int, depending on the backend
+            },
+            'backend': {
+                'type': 'string',
+                'allowed': ["zencoder", "local"]
+            },
+            'status': {
+                'type': 'string',
+                'allowed': ["pending", "waiting", "processing", "finished",
+                    "failed", "cancelled"]
+            },
         }
-    },
-    # Preview parameters:
-    'is_preview': { # Deprecated
-        'type': 'boolean'
     }
 }