Add the official Galaxy Zoo word mark SVG.

As provided under GPL3 by Kyle Willett:
https://plus.google.com/100123542880051296706/posts/WcjVd8zKT7e
ic_toolbar_icon.svg: Resize and resave.

With Inkscape, using the same document height as our
ic_action_invert.svg icon, to make it easier to generate .png files
that are the same height as the action icons in the toolbar.
Generate PNGs for ic_toolbar_icon from the SVG.

By just exporting the SVG from Inkscape with the various
pixel heights listed here for the action icons:
http://iconhandbook.co.uk/reference/chart/android/
Toolbar: Replace the title text with the (word mark) icon.