Downgrade Spring Boot to 1.2.6, Upgrade Groovy to 2.4.5
Downgrade Spring Boot to 1.2.6, Upgrade Groovy to 2.4.5

The downgrade Spring Boot from 1.2.7 to 1.2.6 is necessary because some integration
tests fail with Spring Boot 1.2.7

hwolf/oauth2,hwolf/oauth2,hwolf/oauth2,hwolf/oauth2