Incompatible Confluence Plugins show up as 'Unknown' version in Plugin Repository

Steps to reproduce:

In a fresh install of Confluence 3.2:

• Install Customware Scaffolding Plugin version 3.3.1 using the 'standard' plugin installer (Scaffolding Plugin 3.3.1 is NOT compatible with Confluence 3.2)
• Browse to the 'Plugin Repository'

Expected Results:

• Scaffolding Plugin should be reported as 'Outdated'

Actual Results:

• Scaffolding Plugin is reported as 'Unknown Version'

It appears that the Plugin Repository is only pulling information for plugins that are compatible with the currently running version of Confluence. Unfortunately, users will likely run into this issue if they upgrade Confuence as their plugins aren't automatically upgraded when they upgrade Confluence.

• It might be easier to solve this by making plugins with an 'Unknown Version' more visible in the UI ( CONF-8303 )
• It might also be helpful if plugins were automatically updated when a user upgrades Confluence