Extra command_args in gain_permissions_remove caused silent failure and path never gets deleted.

This passed a symbol to `:except_cops` which caused a .

This avoids an error when RuboCop installed installed yet.

CC @GauthamGoli FYI.

Also, don't delete them after that. This means that `brew postinstall`
becomes a way to easily reinstall configuration files for any formula
without needing any changes to any bottles or requiring a reinstall.

It may not exist before Gem installation which means that the resulting
installed gem will not be found in the PATH.

Also refactor audit cops into two "departments"
 - FormulaAudit
 - FormulaAuditStrict

Current:
```
This formula is keg-only, which means it was not symlinked into /usr/local.

Qt has CMake issues when linked
```

After:
```
This formula is keg-only, which means it was not symlinked into /usr/local,
because Qt has CMake issues when linked.
```

The status code of the last redirect should be 2xx to be deemed successful.

There's been an informal ban for a while but let's
be punchier because this crops up still.

Make sure that `if build.with?` isn't caught.