Add UfrontConfiguration.templatingEngine and defaults.

Also a small fix for loading the ViewEngine by dependency injection.
Cleanup of error page template. Don't rely on bootstrap CDN
Add TemplateData.exists()
Fix for parsing Floats in your controller routing arguments
Add HttpAuthResult for basic HTTP auth...
Fairly major mistake there...
Rename fn to successFn for clarity
Better error messages on 'Bad Request' while performing routing
Fix for async uploads not ever finishing
Various fixes for uploads, functioning well on PHP now.
Add metadata trickery to ViewResult, vastly improve documentation.

Got rid of ViewResult.create() in favour of new ViewResult() also.