Task: Add ability to allow users to view only their own posts

[junlongye]

This is a feature in Manage Posts page where users can see only posts that were posted by them and haven't been deleted.

Task Test:

1. Check if the posts are sorted by time from latest to oldest. (latest will be on the top of the list of posts.)
2. Check if the information of every post in the Manage Posts page can be matched with the information of the posts made by the user. The product name, price, email address, description, phone number, post time, picture, and product id must be the same.
3. Check if all the posts, that were made by the user and haven's been deleted, display in the Manage Posts page.