Cleanups

A few more changes after the performance fixes yesterday, thanks for looking so quickly at those!

The first might be a bit objectionable as it changes the public API, but the 'ToTitleCase' method is no longer used anywhere (in either ServiceStack proper or ServiceStack.Text), so it can be removed. This would also require a corresponding removal of the overrides in the ServiceStack Pcl libraries for Android, iOS, and .NET 4.5.

The second seems less crazy- there seems to be some mixups of override and virtual keyword usage.