fixed some indentation things (just minor stuff) in layout.php
Cleaned up image picker css file (was messy...) and provided a load-picker.js which is doing the actual loading of the jQuery plugin.
Beware: this was already defined in layout.php, but not included in last commit!
Introducing changes to form_select to automatically use 'data-img-src=...' in <option> elements and adding a transparent PNG file for common use in assets (used here for the option unassigned). Currently there is only a test-icon fetched from gravatar, we need a good way to get the email address inside the helper code... :(
Introducing a first test view on the "user chooser" in the "task edit" template.