Remove mongodb dependency from spring-xd-hadoop

- Remove org.springframework.data:spring-data-mongodb:$springDataMongoVersion
  compile dependency from spring-xd-hadoop as this is only needed by
  any module and the module can use spring-xd-extension-mongodb
- Since this removes mongodb on XD admin, launcher classpath, the Mongodb
  autoconfiguration is avoided.
XD-1177: more error checking around labels and indexed modules