fix XMLSource issue in mappings wiki.
Mappings wiki MW is very old and does not include the <ns> element in it's schema.
Issue reported by [1] and was caused by #233 (from @nilesh-c)

[1] http://www.mail-archive.com/dbpedia-discussion@lists.sourceforge.net/msg06248.html
Merge branch 'master' of https://github.com/dbpedia/extraction-framework into feature/all-commons-extractors: combined commons extractors for both.

Conflicts:
	dump/extraction.default.properties
Merge branch 'commons' into feature/all-commons-extractors
Merge pull request #251 from gaurav/feature/all-commons-extractors

Activated all applicable extractors for the Wikimedia Commons
Add possibility to exclude language from import
Merge pull request #250 from dfleischhacker/excludelanguage

Allow to explicitly exclude languages from processing
check if ns exists and require to be the same with wikiTitle
(fix according to comments)
Merge pull request #243 from jimkont/xmlsource

fix XMLSource issue in mappings wiki
Merge pull request #255 from gaurav/feature/unwrapped-self-template

Feature/unwrapped self template
value jsonObject is not a member of object org.json.JSONObject
wikidata toolkit commit
Wikidata Label extractor
WikidataSameAsExtractor
language removed from literal
Generate revision-uris dataset with oldid URIs again
Merge pull request #257 from dfleischhacker/revisionuris

Generate revision-uris dataset with oldid URIs again
WikidataSameAsExtractor, WikidataLabelExtractor changes and WikidataAliasExtractor added
Make constructor arg context public

Needed by ParserUtilsSerializer in distributed-extraction-framework
Merge pull request #258 from nilesh-c/parserutils-context

Make constructor arg context public
WikidataFactsExtractor