HTML5 Canvas + JS Mood Board Editor

General information for the website: A page where people can create mood boards with images and texts
Kind of development: New website from scratch
Num. of web pages/modules: 1
Description of every page/module: We will supply you with all necessary web services to load the available image categories and images from those categories. You should use these services to let people browse images, drag them on to the canvas and resize/rotate them.
Additionally the users should be able to upload images themselves. (Backend services will be supplied by us)
Images with white backgrounds should have the option to convert white to transparent.
And also they should be able to add text, by using about 25 fonts.
Every object should be placed on it's own layer, so that users can move things further to the back or more to the front.

The best example for what we need is right here: http://www.polyvore.com/cgi/app
Description of requirements/features: Should be made by using the following techniques:
HTML5 canvas
JavaScript/jQuery
CSS
Similar urls: http://www.polyvore.com/cgi/app
Extra notes: