(TK-83) Add :enable-trailing-slash-redirect option

Add new :enable-trailing-slash-redirect option to the options map
for all service functions that add handlers. When true, all
requests made to the handler without a trailing slash will be
redirected to have a trailing slash. Defaults to false.
I think maybe we need to be a little more explicit/clear in these docs; if I understand, if you set it to 'true', the server will literally return a redirect response with a 302 status code?  But if you leave it as 'false' (default), then the server will act as though the '/' is implicit and will route the request through to the registered handler, which will be responsible for returning a real response?