[TH] User Upgrades 1.8.1b

Once installed a plethora of features are now available to you:

• User Upgrade Categories
• Search User Upgrades
• Detailed Transaction Log
• Manually Upgrade User

As well as extending upgrades to include:

• Agreement (i.e terms & conditions of the upgrade)
• Redirect
• Button Title
• Show upgrading pricing
• Option to have a tiered upgrades system (only applicable to permanent upgrades)
• Custom end date (useful for pro-rating)
• Option to add a "trial period" for a nominal fee to allow customers to test out upgrades before buying the full upgrade
• Alert users of upcoming upgrade expiration a specific number of days ahead of time (i.e 7 days before expiration)
• Allow for multiple purchases of an upgrade
• Hide upgrades from the available upgrade list, with a specific URL to access the hidden upgrade