Revised Super Download Store v2.3.x to reflect changes based on forum discussions.

Changes:
- Updated Manual Installation Instructions
- Included v2.3.1 Css Button Code changes and Time Stamp Fix (Raiwa)
- Included Code Changes for Download Controller Status (Fa_Demion)

I did not include the PayPal Express changes submitted by Freakez as it is not a viable fix.

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