[JRO] Add route helper & update README

It's a bit presumptuous to add a route at the tail end of a route map -
which is what we're doing currently - so, instead, we should provide an
easy manner to add the route wherever. The route extension should
accomplish that.
Do not throw an exception with no email body.
Merge branch 'master' of https://github.com/jhosteny/griddler