Add Nav Drawer Content for Nav View

[chuckh]

This adds to Nav View the following:

1. Nav Drawer Title
2. Nav Drawer Menu Items
3. paper-toolbar to drawer nav
4. Content Title
5. Increases height of drawer nav toolbar
6. Changes background color of drawer nav toolbar
7. box-shadow to drawer nav

Screenshot

[notwaldorf]

@frankiefu Frankie, do you mind taking a look at this?

[chuckh]

ping @frankiefu.

[frankiefu]

Sorry about the delay. Good work on making it to have more content. I will need to get it reviewed by the designer cause I think they actually want the nav to have no content, and make sure to be consistent with the other templates.

[chuckh]

@frankiefu np. I added some content so it will be clearer for new users of where nav, titles and content go. I did this template to start the discussion. If we move forward with these changes then the other templates should be updated similarly.

[chuckh]

@frankiefu did the designer give any feedback?

[frankiefu]

Sorry @chuckh, still working on it. We are also working potentially having different structures and trying to come up with more app templates e.g. using paper-scroll-header-panel. I will keep you posted.

[chuckh]

@frankiefu sounds good. You might consider having one of the app layouts correspond to Polymer Starter Kit layout. Also I am working on a pull request for PSK to use `paper-scroll-header-panel.

[chuckh]

@frankiefu any news on this?

[cdata]

I have pinged @frankiefu to take a look.

[frankiefu]

We are working on the new app-layout project which will replace this with its own templates here: https://github.com/PolymerLabs/app-layout/tree/master/templates