Toolbar Styling improvements PR

Several toolbar style improvements:

- Height of the toolbar is now 40px (non-retina).
- Background-color is now white #fff by default, and customizable.
- The spacing between all toolbar icons has been removed.
- The toolbar's border-top and divider color has been changed to #c8c8c8
- The toolbar icons normal color is now #7c7c7c and customizable.
- The toolbar divider line is 28px tall (non-retina), and centered.
- Active items are now tinted #0087be (the line that comes up below the icons too).
- The toolbar now collapses when editing the title, since styles can't be used.
The reason why I set `readwrite` explicitly instead of implicitly, is because by adding it you're stating it's writeable by design - some thought was put into it.

When the attribute is missing IMHO, you end up wondering if the developer thought about that at all.  Writing it down, clears up any doubts on the intent.

As an additional bonus, it tends to make properties align better. 👌