Load balancer environment makes form submission SubmittedTime, does not follow timeline

Description

Steps tp reproduce

1. Configure 2 sites: S0 and S10
2. S0 stays on server with timezone = GMT+0
3. S10 stays on server with timezone = GMT+10

Because Forms create the timestamp for Submission by DateTime.Now, Submission.Timestamp depends on server's timezone.

Scenario:
At 15h (GMT+0), Visitor1 submit on S10 ==>record1 is created, and write to Storage with record1.Timestamp = 01:00 02Jan2017
At 23h (GMT+0), Visitor2 submits on S0 ==> record2 is created, and write to Storage with record2.Timestamp = 23:00 01Jan2017

In the period of 15h to 23h (GMT+0) Editor browsing SubmissionView (and even export data) only sees record1, because record2 has not submitted yet.
After 23h (GMT+0), Editor see record1 and record2, but record2 appears earlier in time.

Fix: Depend on CMS.Core 10.5.0