Adding tracing to GraphQL Spring Boot output

[rwilliams-r7]

Currently graphql-spring-boot is using LIB_GRAPHQL_SERVLET_VER = 4.6.0. This does not support tracing in the response.

The latest version https://github.com/graphql-java/graphql-java-servlet/blob/master/src/main/java/graphql/servlet/GraphQLServlet.java adds the tracing data to the response.

This need upgraded to 4.7.0 which supports this.

[rwilliams-r7]

#62

[apottere]

Fixed.