[Sprint: 39] [master+backport] XD-2377 Update "About" section in UI with relevant release links

* Provide XD version info via `/management/info`
* Add AngularJS service to retrieve version info
* Add version info to About page

Jira: https://jira.spring.io/browse/XD-2377


If we use admin controller itself to retrieve the values of `info.build.*` properties then this explicit process can be removed.