Several improvements for the ML engine:

Bug fixes:
* DBPedia Resource URIs are now correctly build for none English texts. The do use now http://{lange}.dbpedia.org/resource/{name}!
* rdf:types are now correctly converted to the DBPedia ontology. Airpedia types where formally used
* dc:type values are now added to the fise:TextAnnotation created for NGram elements of the ML results

New Feature:
* The engine now supports parsing any feature described on http://www.machinelinking.com/wp/documentation/text-annotation/ as property in its configuration. properties need to be prefixed with "ml." (e.g. parsed the "topic" parameter one need to use "ml.topic"). As values Boolean, "true"/"false" and "1"/"0" can be used.
* The engine does now support Topic Classification. This means that fise:TopicAnnotation are created for topics returned by ML. Airpedia Topic URIs are converted to the according DBPedia Resource (default: disabled)
* The engine does now support to include additional entity information (label, abstract, type, depiction, thumbnail) provided by the ML responsee (default: disabled)

other changes:
* added some debug level loggings
* added an unit test with a German text
Added the following features to the ML engine:

* It is now possible to ignore extracted keywords (e.g. if a user just wants topic classification).
* the engine can now create links to the English DBPedia for none English texts. The ML "cross" information are used to do this
* It is now possible to configure multiple engine instances (e.g. for different APP_IDs or different configurations)

Optimization:

* the sent text is no longer in the ML response
* if the processed content does already have a language annotation this language is sent in the ML request. This prevents ML to detect the language a 2nd time.
* the default parameters of the ML client API (enable everything) are now overridden to only include those items really required by the engine

Other Changes

* The Engine uses now constants defined by the ParamsValidator (ML API client) instead of its own strings
* Organized Imports
Merge branch 'upstream' to 'master' and resolved all conflicts