Add a scheduled task to update prices from Amazon
Add user tagline to profile page
Tweak pledge display

* Add header
* Add placeholder when no active pledge
Refactor profile controller routing

The ProfileController is now the ProfilesController and uses standard
Rails RESTful resource routing. (Also cleaned up a vestigial
before_filter in the HomeController.)
DRY up signup forms with a profile fields partial
Minor simplification in profile controller

Refer to @current_user just as @user. Makes some standard stuff easier
in the forthcoming edit/update actions
Add profile edit functionality