Move Mnemonic to the Attic

1. Confirm Board Resolution
2. Inform dev of the move to the Attic
3. Create project page on Attic site: http://attic.apache.org/projects/mnemonic
4. Ensure original project site pages carry the Attic banner
5. Update the project DOAP file (if any) or copy to projects-override: N/A - no DOAP
6. Get infra lock down project's resources INFRA-26750
7. Announce on announce at apache.org

See http://attic.apache.org/process.html#howto for detailed instructions