refs https://github.com/TryGhost/Toolbox/issues/583
- removed default config so we just have separate numbers for the flags
- added threshold to flags config so we can protect against small
changes in variance
refs https://github.com/TryGhost/Toolbox/issues/583
- this commit adds config for codecov because this repo needs some
changes that aren't suitable for the global config
- this probably needs some adjusting over time but should get us started
for now
