Add whole note SVG found online

Source: http://commons.wikimedia.org/wiki/File:Music-wholenote.svg
Remove staff lines from whole note SVG
Delete unneeded tags and attrs in whole note SVG
Convert whole note SVG to React component
Use `viewBox` to match size of whole note to staff
Render whole note on a line or space in the staff

Add `staffPosition` prop, which is zero-indexed from the bottom line
in the staff (treble clef E) upward. So `0` puts the whole note on
E, `1` on F, etc.
Take advantage of ES6 syntax in object literal

`{y}` is short for `{y: y}`.
Merge branch 'whole-note'