Fix jpa example to specify the h2 database (#24)

diff --git a/camel-example-spring-boot-rest-jpa/src/main/resources/application-dev.yml b/camel-example-spring-boot-rest-jpa/src/main/resources/application-dev.yml
index de09a57..ae9ae34 100644
--- a/camel-example-spring-boot-rest-jpa/src/main/resources/application-dev.yml
+++ b/camel-example-spring-boot-rest-jpa/src/main/resources/application-dev.yml
@@ -31,6 +31,11 @@
     # Let Spring Boot auto-configure an embedded HSQL database
     url:
 
+  # Spring Data JPA configuration
+  jpa:
+    database: h2
+    database-platform: org.hibernate.dialect.H2Dialect
+
 # The application configuration properties
 example:
   generateOrderPeriod: 2000