explicitly add hibernate validator

based on the spring-boot commit, it became optional in spring-boot-actuator
https://github.com/spring-projects/spring-boot/commit/433d049544c9c3cf519f3e76c8dab5e818b1b46c
upgrade spring-boot to 1.0.0.BUILD-SNAPSHOT

spring-boot bumped version
https://github.com/spring-projects/spring-boot/commit/68293f34af439aa96811fb6218d53b2e69231d74