Make DBPedia Spotlight endpoint configurable

[jnehring]

Please find the part in e-Entity repo that configures the endpoint of DBPedia Spotlight. Then make it configurable via Spring externalized configuration:

http://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html

The default value should be the original DBPedia Spotlight endpoint.

More documentation: http://www.mkyong.com/spring3/spring-value-default-value/

Please implement it in a branch and do not merge it in the master branch before november 12th.

[josauder]

Implemented in branches Broker:integration-tests and e-Entity:configurableEndpoint. See freme-project/Broker#124 for more implementation details