Order routes for Swagger Api alphabetically

Currently there is no ordering being supplied to the routes being retrieved for Swagger documentation. They maintain the same order from when they were [added to the ServiceMetaData class] (https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Api.Swagger/SwaggerResourcesService.cs#L58). This can lead to the routes getting jumbled around as more are added.

Instead, they should be sorted alphabetically. There is already an alphabetical sorting being performed on the [individual base routes] (https://github.com/ServiceStack/ServiceStack/blob/master/src/ServiceStack.Api.Swagger/SwaggerApiService.cs#L173), just none yet being done here at the base level.