Sorted and cleaned up _pom.xml
- included Maven-SortPom-Plugin
- removed Maven-Eclipse-Plugin
  (Javadoc and sources download should be a user setting)
- sorted _pom.xml
- simplified _pom.xml by disabling ES6 delimiters
Merge branch 'feature/sort_pom_template' of https://github.com/logann-it/generator-jhipster into logann-it-feature/sort_pom_template
- re-included automatic downloads of sources and javadoc
Merge branch 'feature/sort_pom_template' of https://github.com/logann-it/generator-jhipster into logann-it-feature/sort_pom_template
Merge branch 'logann-it-feature/sort_pom_template'