Fixing problem in PR 559

[lfoppiano]

I've added two new methods in the GrobidProperties that allow to:

• get all the engines selected individually in the configuration
• get all possible engines needed (result of the above point and the engine selected in the grobid.crf.engine property.

When running LibraryLoader.load() instead of checking only the value of grobid.crf.engine I consider the list of specified engines.

[coveralls]

Coverage increased (+0.02%) to 38.188% when pulling adc0a94 on bugfix/problem-pr-559 into b0560b5 on master.

[de-code]

Looking good too me. Thank you for doing that.

[lfoppiano]

Thanks @de-code for checking it out. I move it to "ready".

[lfoppiano]

(I suggest to also apply #620, as it's touching a similar part)

[lfoppiano]

@de-code Thanks for the feedback. I pushed a fix.

[kermitt2]

Very readable, tested and it fixes the problem raised in PR #559, thanks a lot!
It's much easier with this fix to specify a couple of models with DeLFT, the rest with Wapiti - which is the best config currently in term of accuracy (the 2 DeLFT models to use for this being the citation model and the affiliation-address model).