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.
@aerych - Sounds good.  One question though: I've used the hex methods for colors that are not present in WPStyleGuide.  I was wondering if I should be adding these colors to it at all - and if so who chooses the new names for the colors.