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
if user also adds @EnableWebMvcSecurity. The problem is that the ordering
of the init() and configure() methods in the Spring Security configurers
can force things to happen too early unless we are careful. It's still a bit
twitchy I would say, but this relatively small change seems to fix the GS guide
and not break any existing tests.
I added a sample which mimic ths GS guide so we get an integration test that
executes the new code paths.
Fixes gh-1364
