Add support to change the default time filter range

Default is 6h it seems.  This change allows adjusting the default
to/from range in the time filter.

Change-Id: I567b9cc5cd8c753f852066c9e6868dd0f1b30b60

grafana_dashboards/schema/dashboard.py

@@ -25,6 +25,10 @@ class Dashboard(object):
             v.Required('timezone', default='utc'): v.Any('browser', 'utc'),
             v.Required('title'): v.All(str, v.Length(min=1)),
             v.Optional('id'): int,
+            v.Optional('time'): {
+                v.Required('from'): v.Any(v.Datetime(), str),
+                v.Required('to'): v.Any(v.Datetime(), str),
+            },
         }
         rows = Row().get_schema()
         dashboard.update(rows.schema)

tests/schema/fixtures/dashboard-0021.json

@@ -50,6 +50,10 @@
                     }
                 ]
             },
+            "time": {
+                "from": "2018-02-07T08:42:27.000Z",
+                "to": "2018-02-07T13:48:32.000Z"
+            },
             "timezone": "utc",
             "title": "New dashboard"
         }

tests/schema/fixtures/dashboard-0021.yaml

@@ -1,4 +1,7 @@
 dashboard:
+  time:
+    from: "2018-02-07T08:42:27.000Z"
+    to: "2018-02-07T13:48:32.000Z"
   templating:
     - name: hostname
       type: query

tests/schema/fixtures/dashboard-0022.json

@@ -0,0 +1,46 @@
+{
+    "dashboard": {
+        "new-dashboard": {
+            "rows": [
+                {
+                    "collapse": false,
+                    "editable": true,
+                    "height": "250px",
+                    "panels": [
+                        {
+                            "bars": false,
+                            "editable": true,
+                            "error": false,
+                            "fill": 1,
+                            "lines": true,
+                            "linewidth": 2,
+                            "percentage": false,
+                            "pointradius": 5,
+                            "points": false,
+                            "span": 12,
+                            "stack": false,
+                            "steppedLine": false,
+                            "targets": [],
+                            "title": "no title (click here)",
+                            "type": "graph",
+                            "x-axis": true,
+                            "y-axis": true
+                        }
+                    ],
+                    "showTitle": false,
+                    "title": "New row"
+                }
+            ],
+            "templating": {
+                "enabled": false,
+                "list": []
+            },
+            "time": {
+                "from": "now-1h",
+                "to": "now"
+            },
+            "timezone": "utc",
+            "title": "New dashboard"
+        }
+    }
+}

tests/schema/fixtures/dashboard-0022.yaml

@@ -0,0 +1,11 @@
+dashboard:
+  title: New dashboard
+  time:
+    from: now-1h
+    to: now
+  rows:
+    - title: New row
+      height: 250px
+      panels:
+          - title: no title (click here)
+            type: graph