Propagate build displayName to URL

This change allows HTTP clients to access builds by its `displayName`. This is useful for tools accessing jenkins builds using some known identifier without the need to known the build number (especially when used together with [build-name-setter-plugin](https://github.com/jenkinsci/build-name-setter-plugin)).

In case of name collision, newer build is picked.

Version string is a handy example  `/job/jenkins-lts/1.480.3-SNAPSHOT`.