Respect report-width setting when presenting error messages to end users for --sniffs and --exclude paramaters

[fredden]

While working on #344, some additional improvements were raised. In order to not forget about the suggestion, this issue has been opened.

When reporting errors with the --sniffs or --exclude parameters, the error message does not respect the report-width which may have been set. It would be preferable for this width to be taken into account while preparing / presenting messages to the user - even error messages.