Consistency and UI improvements for gadget directory

There are a few consistency problems that would be good to fix in the new Gadget Directory before we ship it.

• The wording 'Click here for ...' is against our conventions for link text in Confluence. We don't say 'Click here', rather the link text should be a description of what is found at the destination of the link. Change this to something like 'Confluence Gadget Documentation'.
• The text 'Click here for ...' is too large. It should be the same size as the text above it.
• There is a hover background colour on the gadget specs, but they aren't clickable. You should only use hover highlighting when the target is clickable.
• The description for the Activity Stream says, 'Lists recent activity in a single project, or in all projects.', but we don't have projects in Confluence. Should it say 'space'/'spaces' instead?
• The gadget thumbnails are scaled down here like in the macro browser when they don't need to be. (I presume they're scaled down. If they're not, we need to recreate those images because they look badly scaled.)

Some improvement ideas:

• Make the text 'By Atlassian' and 'Gadget URL' smaller (or greyer, or both) so that the title and description are more obvious. The latter are the important pieces of information, so they should stand out a bit more.
• Make the font for the description text in the left panel the same size as the body font on the right-hand side.
• Put some short introductory text in the dialog. Either above the 'How to use these gadgets' on the left, or in a panel above the gadgets on the right. It should explain what gadgets are: 'Gadgets allow you to display Confluence content and information in other applications.'