Change LICENSE to GNU Affero

With these changes, commercial use is still allowed, but are required to disclose the source, changes, and copyright. Meaning that people won't be unknowingly ripped off, and would be paying knowing that it is an open-source project with possible changes.

tl;drLegal link: https://tldrlegal.com/license/gnu-affero-general-public-license-v3-(agpl-3.0)