Admin tweaks - Delete stream badges and change logic for build submission rejections

Description

Couple of tweaks in /admin:

When a grant is in approved status, users can submit their builds to be able to complete their grant and receive the rest of their grant amount (if admins approve the build proposal).

In case the build is not complete, and admins want to reject the build submissions, changed the logic of reject action, to change the status of the grant to "approved" instead of "rejected", so users can resubmit the build when they fix their problems. The condition I'm checking is if the current status of the grant prior executing the rejection logic was "submitted".

The reject/approval notes were always showing in /my-grants for grants in approved status, so didn't need to tweak it.

Closes #123
Also deleted stream badges since regular streams don't exist anymore.

Closes #124