It's better maintained and it seems to provide more features
as well.

Vet, Owner, Visit. The Visit "aggregate" is a little artificial
but it demonstrates a useful point about not holding on to
references of "parent" (reference data) objects, i.e. the Visit has
an Integer petId, instead of a Pet field. In principle this app is
now almost ready to migrate to multiple services if anyone wanted
to do that.

Upgrade to Ehcache 3 and Java config

I saw on twitter the reference of an article (in french):
http://javaetmoi.com/2016/08/migrer-vers-spring-boot/

That article concludes with something along the lines of  "Besides the
EhCache and Maven configuration, Petclinic does not hold a single line
of XML anymore".

Looking at the code, we can remove more XML if you want. This PR migrates
the cache infrastructure to EhCache 3 and JCache (JSR-107). This also
reduces the number of dependencies.

Conflicts:
	pom.xml
	readme.md
	src/main/java/org/springframework/samples/petclinic/repository/jdbc/JdbcPetRepositoryImpl.java
	src/main/java/org/springframework/samples/petclinic/web/VetController.java
	src/test/java/org/springframework/samples/petclinic/web/CrashControllerTests.java
	src/test/java/org/springframework/samples/petclinic/web/OwnerControllerTests.java
	src/test/java/org/springframework/samples/petclinic/web/PetControllerTests.java
	src/test/java/org/springframework/samples/petclinic/web/VetControllerTests.java
	src/test/java/org/springframework/samples/petclinic/web/VisitControllerTests.java