Wikidata integration + Refactoring Core to accept new formats 

#### This pull request is mainly the output of GSoC2013 [Wikidata Integration inside DBpedia Project](https://github.com/dbpedia/extraction-framework/wiki/GSOC2013_Progress_Hady-Elsahar)

- added JsonParser to Parse Json Pages Extracted from Wikidata 
- added multiple Extractors to Extract Triples out of Wikidata Json Dumps 
- updating the ontology file by adding Wikidata to  DBpedia mappings for Properties and Types in the Mappings wiki 
- the core refactoring issue #38  to easily accept new Page formats Like Json in case of Wikidata 

#### there are two main Issues left to be done after the merge : 

1 - there are two warnings left for JsonLift: 'withFilter' method does not yet exist on net.liftweb.json.JsonAST.JValue, using `filter' method instead, try mvn clean install to see them

2- the Design of the Wikidata Extractors and [JsonWikiParser](https://github.com/hadyelsahar/extraction-framework/blob/wikidata/core/src/main/scala/org/dbpedia/extraction/wikiparser/impl/json/JsonWikiParser.scala) , were temporary design to cope with the old core , now the new core is redesigned so what we should do : 
- JsonNode should hold a JsonObject, not a list of Nodes
- move all the extra code from JsonParser (that generates AST) into the individual extractors Every extractor should define at the beginning variables with the paths that are of interest (e.g. json \ "claims" \ ...) and later reuse these variables. 
- Create org.dbpedia.extraction.util.JSONUtils where you can store all the Json related custom function you create
- adapt the Wikidata Extractors to new Wikidata Json Changes