Move logic to append multi-segment slug route pattern to a config post processor

[acelaya]

Currently, the logic is in the routes.config.php file, and in the rest module ConfigProvider, which is called from the previous file.

That means the env var is read in two places, making it harder to override via config.

Remove the logic from the two files mentioned above, and the access to the env var, and create a post processor that iterates over all routes, and replaces {shortCode} by {shortCode:.+} if the config flag is true.