Good Ghosting Core Files Audit

Summary

During auditing, we found `3` potential issues of various levels of severity: `1` low-severity, and `2` informational-level findings. We made `1` best practices recommendations. We recommend addressing the findings before going live. <br><br> **Disclaimer:** For the current audit, Quantstamp was requested to audit only the following core files of the project: `GoodGhosting.sol`, `GoodGhostingPolygon.sol`, `GoodGhostingPolygonWhitelisted.sol`, `MerkleDistributor.sol`. <br><br> **2021-08-09 update**: during this reaudit, the admin team has brought all of the status of findings either into fixed or acknowledged. In addition, QSP-4, is uncovered by GoodGhosting team and discussed with Quantstamp team. Furthermore, the branch coverage of the tests has been increased from `89.44%` to `90.51%`.