Minor tweaks of the Toolbar design.

- Made the drop shadow under the toolbar a bit more subtle.
- Made the toolbar color a bit lighter.
- Decreased the font size of the search hint text.
- Made the background of the SearchView be the same as the placeholder.
- Removed the Submit button from the SearchView (the "go" button on the
  keyboard still applies).
- Removed the magnify icon from the SearchView when active.
- Fixed checkstyle.

Change-Id: Ic1ace7a314d80c46c48a4cf88a899f5fcebe8dcf