Make verifyExceptionMessage() support scrubbers

[claremacrae]

This would be trivial to implement. It could be useful if the exception text contains some changing data.

[claremacrae]

Hmmmm - maybe it already does - a test to confirm this would be useful.

[claremacrae]

If it does, then we would just need to remove the Doxygen comment that says that it does not support scrubbers...

[claremacrae]

This is invalid - I remembered wrongly, it's this one that does not support scrubbers:

        /// Note that this overload ignores any scrubber in options
        static void verify(const ApprovalWriter& writer,
                           const Options& options = Options())
        {
            FileApprover::verify(*getDefaultNamer(), writer, options.getReporter());
        }
        ///@}

Marking this as invalid and closing...