Update delete test (influxdata#50)

Author: rolincova

Client.Test/ItDeleteApiTest.cs

@@ -136,11 +136,17 @@ public async Task Delete()
  Assert.AreEqual(6, tables[0].Records.Count);
 
  _deleteApi = Client.GetDeleteApi();
- await _deleteApi.Delete(DateTime.Now.AddHours(-1), DateTime.Now, "", _bucket, _organization);
+ await _deleteApi.Delete(DateTime.Now.AddSeconds(-1), DateTime.Now, "", _bucket, _organization);
 
  var tablesAfterDelete = await _queryApi.QueryAsync(query, _organization.Id);
 
- Assert.AreEqual(0, tablesAfterDelete.Count);
+ Assert.AreNotEqual(0, tablesAfterDelete.Count);
+ 
+ await _deleteApi.Delete(DateTime.Now.AddHours(-1), DateTime.Now, "", _bucket, _organization);
+ 
+ var tablesAfterDelete2 = await _queryApi.QueryAsync(query, _organization.Id);
+ 
+ Assert.AreEqual(0, tablesAfterDelete2.Count);
  }
  }
 }