Timestamps inaccurate after migrating discussions to MySQL backend

[asadali145]

Steps to Reproduce

1. Disable MySQL Backend
2. Create posts and comments
3. Enable MySQL backend
4. Migrate data from MongoDB to MySQL
5. Notice that the post/comments time is set to the time we ran the command.

Expected Behavior

Timestamps remain the same as before the migration

Actual Behavior

Timestamps are not preserved

[taimoor-ahmed-1]

Issue resolved: #262