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