promise: Use UTC time for collector.db promises

Collector db is fixed to store UTC times, so those promises need to follow.

slapos/promise/check_computer_memory/__init__.py

@@ -81,7 +81,7 @@ def main():
   args = parser.parse_args()
 
   # get last minute
-  now = datetime.datetime.now()
+  now = datetime.datetime.utcnow()
   currentdate = now.strftime('%Y-%m-%d')
   delta = datetime.timedelta(minutes=1)
   currenttime = now - delta

slapos/promise/check_user_memory/__init__.py

@@ -83,7 +83,7 @@ def main():
 
   result, message, error = checkMemoryUsage(
     database_path,
-    datetime.now(),
+    datetime.utcnow(),
     user=args.user,
     threshold=args.threshold,
     unit=args.unit,

slapos/promise/plugin/check_free_disk_space.py

@@ -207,7 +207,7 @@ is assumed constant and used to predict in how many days the disk would become f
       disk_partition = self.getConfig('test-disk-partition', '/dev/sda1')
     else:
       # get last minute
-      now = datetime.datetime.now()
+      now = datetime.datetime.utcnow()
       currentdate = now.strftime('%Y-%m-%d')
       currenttime = now - datetime.timedelta(minutes=1)
       currenttime = currenttime.time().strftime('%H:%M')