Fix Jasper on Tomcat 8

Refactor Jasper initialization code to call JasperInitializer during
server start.

Fixes gh-962
See gh-919

spring-boot-samples/pom.xml

@@ -39,6 +39,7 @@
 		<module>spring-boot-sample-simple</module>
 		<module>spring-boot-sample-tomcat</module>
 		<module>spring-boot-sample-tomcat-multi-connectors</module>
+		<module>spring-boot-sample-tomcat8-jsp</module>
 		<module>spring-boot-sample-traditional</module>
 		<module>spring-boot-sample-web-method-security</module>
 		<module>spring-boot-sample-web-secure</module>