- introduces the methods AgaviController::checkActionFileExists() and AgaviController::checkViewFileExists()
- adds the method AgaviToolkit::canonicalName()

- changes AgaviController::createActionInstance(), AgaviController::createViewInstance() to use above methods
- changes all appropriate places to use AgaviToolkit::canonicalName() instead of str_replace(...)

- changes AgaviExecutionFilter::execute() appropriately 

- fixes sanity checks for Action and View names, fixes #780
- refs #829