Implementing a dummy-model

[lfoppiano]

The advantages:

• possibility to test parser class side methods
• remove the needs of having the grobid home around (a particular problem for sub-modules)

Implementation:

• added a GrobidModels.DUMMY
• added a DummyTagger which is returned from TaggerFactory only for GrobidModels.DUMMY and tags everything as <dummy>

This was mentioned in issue #410

[coveralls]

Coverage increased (+0.2%) to 38.204% when pulling 5ac80f5 on dummy-model-for-test into 0dfd457 on master.

[lfoppiano]

Used in the following: https://github.com/lfoppiano/grobid-superconductors/blob/master/src/test/java/org/grobid/core/engines/SuperconductorsParserTest.java

Excerpt:

public class SuperconductorsParserTest {

    private SuperconductorsParser target;

    private ChemDataExtractionClient mockChemspotClient;

    @Before
    public void setUp() throws Exception {
        mockChemspotClient = EasyMock.createMock(ChemDataExtractionClient.class);
        target = new SuperconductorsParser(GrobidModels.DUMMY, mockChemspotClient);
    }
[...]

I will write a few unit tests around it