TR download zip changes

When you download a theme from ThemeRoller, it should include all CSS Framework dependencies and widget css files. In website trunk, this is currently working fine.

Secondly, The zip should unzip to a folder of the same name. In other words, all of the files inside the zip should be enclosed in a folder called "jquery-ui-themeroller". This alreay happens on mac but PC users get the files uncontained, which is messy.

Then, all CSS files and the images directory should be contained in a folder called "theme" and demo.html should be updated to link to that folder. The final zip hierarchy should look like this:

jquery-ui-themeroller.zip

unzipped folder:

jquery-ui-themeroller

---demo.html (static)

---theme/

------ui.core.css

------ui.all.css

------ui.allplugins.css

------ui.accordion.css

------ui.datepicker.css

------ui.dialog.css

------ui.progressbar.css

------ui.resizable.css

------ui.slider.css

------ui.tabs.css

------ui.theme.css (generated from TR)

------images/

---------[theme images] (generated from TR)