Add timezone to snapshot timestamp (#360)

* Add timezone to snapshot timestamp

```
old: 2018-02-14T15:13:46.391829
new: 2018-02-14T15:13:46.391829+00:00
```

* Update __init__.py

* Move code to dt util

* Lint

* Lint 2

* Update dt.py

* Update __init__.py

hassio/snapshots/__init__.py

@@ -1,6 +1,5 @@
 """Snapshot system control."""
 import asyncio
-from datetime import datetime
 import logging
 from pathlib import Path
 
@@ -9,6 +8,7 @@ from .utils import create_slug
 from ..const import (
     FOLDER_HOMEASSISTANT, SNAPSHOT_FULL, SNAPSHOT_PARTIAL)
 from ..coresys import CoreSysAttributes
+from ..utils.dt import utcnow
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -33,7 +33,7 @@ class SnapshotManager(CoreSysAttributes):
 
     def _create_snapshot(self, name, sys_type, password):
         """Initialize a new snapshot object from name."""
-        date_str = datetime.utcnow().isoformat()
+        date_str = utcnow().isoformat()
         slug = create_slug(name, date_str)
         tar_file = Path(self._config.path_backup, f"{slug}.tar")
 

hassio/utils/dt.py

@@ -8,6 +8,8 @@ import aiohttp
 import async_timeout
 import pytz
 
+UTC = pytz.utc
+
 _LOGGER = logging.getLogger(__name__)
 
 FREEGEOIP_URL = "https://freegeoip.io/json/"
@@ -61,7 +63,7 @@ def parse_datetime(dt_str):
 
     tzinfo = None  # type: Optional[dt.tzinfo]
     if tzinfo_str == 'Z':
-        tzinfo = pytz.utc
+        tzinfo = UTC
     elif tzinfo_str is not None:
         offset_mins = int(tzinfo_str[-2:]) if len(tzinfo_str) > 3 else 0
         offset_hours = int(tzinfo_str[1:3])
@@ -74,3 +76,8 @@ def parse_datetime(dt_str):
     kws = {k: int(v) for k, v in kws.items() if v is not None}
     kws['tzinfo'] = tzinfo
     return datetime(**kws)
+
+
+def utcnow():
+    """Returns current timestamp including timezone."""
+    return datetime.now(UTC)