Project approvals and flash

There's now a new URL, `/admin/approve`, where you can see all the unapproved projects, go to their project pages, and approve them. Project leaders can't edit their pages until the project is approved—not sure if that's the desired behavior. Only admins can approve the project.

The flash directive works pretty simply: whenever you want an alert to the user, do

    $scope.$emit("flash", {state: "error|success", msg: "the next you want to display"})

An example is in `marketplace.js` around line 70.