Add missing features for Weight Paint: Gradient Tool, symmetry & front face only

Weight Paint: Gradient Tool

When you use the normal brush, blur, smear etc to weight paint, you have options to enable X-axis symmetry and to paint Front Faces Only.

I am currently using 4.2.2, and when using the Gradient Tool to weight paint, I can't see any "Front Face Only" option and the X-axis symmetry doesn't work, which limits the usefulness of the brush.

So my suggestion would be to add X-axis symmetry and Front Face Only as options when using the Gradient tool to weight paint. It would make it more useful and also make it consistent with how the other brushes can be used.