Fix polymer UI

@terrylucas @dinhviethoa 

Sorry, it's a giant CL, but there are almost no real changes. The trivial ones are:

1) Resynced the CSS between non-polymer and polymer UIs (fixed a few problems)
2) Fixed/improved whitespace, indentation, etc. in the widgets
3) Moved the images used in widgets (internal and external) to better locations
4) Fixed the way the images were referenced for/in the widgets

The changes that are real are:
1) Fixed the name of the 'touch-action' attribute on spark-toolbar
2) Added and used the 'color' attribute on spark-toolbar
3) Fixed the splitview, which became invisible after an update to the newest polymer_elements
4) Fixed the position of the hotdog menu button
5) Changed the base class of the new widgets to src/Widget - the main change in behavior that that achieves is that the author styles are now applied to comprising parts of the widget (in particular, the Bootjack styles).

I've also tried to fix the image alignment in the hotdog menu button, and the margins in the menu itself, but so far unsuccessfully.