Calcite-bootstrap-dark.css needs additional styling

The new calcite-bootstrap-dark.css is close but needs additional styling to support all bootstrap components. More specifically:
- Navbar font colors
- Navbar top highlight (should it still be blue?)
- Panel background headers
- Tab background/foreground
- Textbox borders
...

We should also document what css people should use with dark.css + navbar. e.g. navbar-default or navbar-inverse or none.

Here's a [test app](http://output.jsbin.com/zobozi) that illustrates the issues.