Auto-configure Spring Security OAuth2 when detected on the classpath

* Automatically spin up Authorization Server and Resource Server
* Automatically configures method level security included OAuth2Expression handler
* Wrote extensive unit tests verifying default behavior as well as the auto-configuration backing off when custom Authorization/Resource servers are included
* Created org.springframework.boot.security.oauth2 subpackage to contain it
* Can also disable either resource of authorization server completely with a single property for each
* Print out the auto-generated secrets and other settings
* Added spring-boot-sample-secure-oauth2 to provide a sample that can be run and poked with curl as well as some automated tests.
* Make users ask for which servers to install by adding @Enable*
* User has to @EnableGlobalMethodSecurity instead of using properties files

Add Spring Security OAuth2 support to Spring Boot CLI

* Triggered from either @EnableAuthorizationServer or @EnableResourceServer
* Needs to have @EnableGlobalMethodSecurity to allow picking the annotation model.
* By default, comes with import support for @PreAuthorize, @PreFilter, @PostAuthorize, and @PostFilter via a single start import
* Also need import support for the enable annotations mentioned above.
* Added extra test case and sample (oauth2.groovy)

spring-boot-samples/spring-boot-sample-secure-oauth2/src/main/resources/application.properties

@@ -0,0 +1,8 @@
+spring.datasource.platform=h2
+spring.oauth2.client.client-id=foo
+spring.oauth2.client.client-secret=bar
+
+security.user.name=greg
+security.user.password=turnquist
+
+logging.level.org.springframework.security=DEBUG

spring-boot-samples/spring-boot-sample-secure-oauth2/src/main/resources/data-h2.sql

@@ -0,0 +1,4 @@
+insert into FLIGHT
+(id, origin, destination, airline, flight_number, traveler)
+values
+(1, 'Nashville', 'Dallas', 'Spring Ways', 'OAUTH2', 'Greg Turnquist');