Improved Dashboard landing page

[boonebgorges]

As discussed internally, we will add a landing page to the PressForward item in the Dashboard menu:

This landing page would appear when clicking Dashboard > PressForward, instead of All Content. The landing page would include information about the current installation - chosen statistics, etc. And it would have some inline documentation, including an overview of the two methods for getting content into PressForward (RSS subscriptions and Nominate This), and links to external documentation pages that describe the setup process.