extracted article service into generic service in utils

vipra-rest/src/main/java/de/vipra/rest/model/Article.java

...src/main/java/de/vipra/rest/resource/ArticleResource.java

...in/java/de/vipra/rest/serializer/ArticleDeserializer.java

...main/java/de/vipra/rest/serializer/ArticleSerializer.java

...st/src/main/java/de/vipra/rest/serializer/JsonHelper.java

...t/src/main/java/de/vipra/rest/service/ArticleService.java

vipra-util/.classpath

vipra-util/.settings/org.eclipse.jdt.core.prefs

...l/.settings/org.eclipse.wst.common.project.facet.core.xml

...-util/src/main/java/de/vipra/util/helper/MongoHelper.java

vipra-util/src/main/java/de/vipra/util/model/Article.java

vipra-util/src/main/java/de/vipra/util/model/Model.java

...til/src/main/java/de/vipra/util/service/ModelService.java