Recolor Error: Switching from swatch with custom thumbnail to one without does not update

[Stacey Haffner]

Repro Steps:

1. View Swatch that has a custom Thumbnail
2. Click on swatch that does not have a custom thumbnail

Expected Behavior:

Swatch preview will display what the swatch is, including nothing if the swatch does not exist.

Actual Behavior:

Swatch image persists when there is not a swatch associated with the swatch thumbnail.

[Stacey Haffner]

Duplicate of issue #27

[Stacey Haffner]

Merged into master.