The HATEOAS sample does not support XML responses. Previously, the
controller doesn't constrain the media types that it could produce.
This would result in a failure when handling a request that prefers
XML responses.
This commit updates the produces clauses in the controller so that
the sample will only attempt to produce JSON.
Closes gh-4343
Given that Spring Boot uses java config accross the board, a new `value`
attribute is now aliased to the existing `classes` attribute such that
one could write the following:
@SpringApplicationConfiguration(MyConfig.class)
public class MyTest {}
Closes gh-3635
Andy Wilkinson
Huang YunKun
Phillip Webb
Stephane Nicoll