Allow using gradient fills in shape tools

[adroitwhiz]

Expected Behavior

When drawing shapes with shape tools (oval + rectangle), there should be a way to draw them with a gradient fill.

Actual Behavior

You have to draw ovals and rectangles with a solid fill, and then change the gradient type in the color picker.

Steps to Reproduce

1. Switch to the rectangle or oval tools
2. Notice the lack of a gradient type selector in the color picker

Operating System and Browser

All

[adroitwhiz]

Closed in #1004