Google Cloud Storage support

We introduce a new node_type, storage, which can support different file
storage backends and makes them available for browsing via dedicated
entry points in the application. We intend to keep pillar storage
agnostic and support both internal/local storages as well as
remote/hosted solutions.

pillar/manage.py

@@ -636,6 +636,40 @@ def populate_node_types(old_ids={}):
         }
     }
 
+    node_type_storage = {
+        'name': 'storage',
+        'description': 'Entrypoint to a remote or local storage solution',
+        'dyn_schema': {
+            # The project ID, use for lookups in the storage backend. For example
+            # when using Google Cloud Storage, the project id will be the name
+            # of the bucket.
+            'project': {
+                'type': 'objectid',
+                'data_relation': {
+                    'resource': 'nodes',
+                    'field': '_id'
+                },
+            },
+            # The entry point in a subdirectory of the main storage for the project
+            'subdir': {
+                'type': 'string',
+            },
+            # Which backend is used to store the files (gcs, pillar, bam, cdnsun)
+            'backend': {
+                'type': 'string',
+            },
+
+        },
+        'form_schema': {
+            'subdir': {},
+            'project': {},
+            'backend': {}
+        },
+        'parent': {
+            "node_types": ["group", "project"]
+        }
+    }
+
     from pymongo import MongoClient
 
     client = MongoClient(MONGO_HOST, 27017)
@@ -671,6 +705,7 @@ def populate_node_types(old_ids={}):
     # upgrade(comment_node_type, old_ids)
     upgrade(project_node_type, old_ids)
     upgrade(asset_node_type, old_ids)
+    upgrade(node_type_storage, old_ids)
 
 
 @manager.command