Previously, native cache libraries were favored over a standard JSR-107
implementation. If a user has a working setup using JCache with one
provider and switch to another provider, his setup may be broken if we
happen to provide a native support for the new provider.
We now consistently favor JSR-107 if it is present. Native support can
still be enabled via the `spring.cache.type` property.
Closes gh-3822
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