Remove the Value abstraction in the request

Parameters and path variables now return String. Checking for nulls
was inconvenient.
Value is now a utility class inside the util package.
Add the missing HTTP methods.

Add all the HTTP methods to Route.
Create convenient methods in Jogger for PUT and DELETE.
Remove the Exception and NotFound handling

We don't need to provide another mechanism for exception and 404
handling. That's what interceptors are for.
Remove dependency between Request and Route

All we need in the Request is the route path, which can be null.
Code quality improvements proposed by Sonar
Improve the getting started section