Is your feature request related to a problem? Please describe.
Currently, the selling tab excludes grey items. They are now transmogable and, therefore worth putting up for auction.

Describe the solution you'd like
I would like an option to allow grey items to populate in the selling tab without having to add them in one at a time. Actually, it would be great to have an option to select which quality items someone would like to sell. For instance, I know people that won't waste time with anything that isn't epic or rare. This would be helpful for them.

Describe alternatives you've considered
The only alternative is to click on the grey items one at a time. However, I have amassed quite a few in preparation for the patch that just came out allowing grey items to be transmoged. I look for more people to be buying greys and for them to sell for way more than they should. I feel like this should be a fairly easy addition to the addon, and one that many would benefit from.

Additional context
This addon is a lifesaver. Thank you for your hard work on it! I am amazed at all it does!