launch a tdbquery on multiple location

[Steven Blanchard]

Hello,

I would like to know if it is possible to perform a query with 
tdb2.tdbquery on multiple tdb folder?

It is possible to put several times the --loc argument in the command 
line but in the results, I have only the triple matches to the 2nd 
folder.

example with Order 1 :
```bash
apache-jena-4.7.0/bin/tdb2.tdbquery --loc Demo_2/ --loc Demo_1/ --query 
demo.sparql

?s      ?p      ?o
<<http://example.org/#spiderman>>   
<<http://www.perceive.net/schemas/relationship/enemyOf>>    
<<http://example.org/#green-goblin>>
```

example with Order 2:
```bash
apache-jena-4.7.0/bin/tdb2.tdbquery --loc Demo_1/ --loc Demo_2/ --query 
demo.sparql

?s      ?p      ?o
<<http://example.org/#spiderman>>	<<http://www.perceive.net/schemas/relationship/loveOf>> 
<<http://example.org/#lois_lane>>
```

demo.sparql:
```sparql
SELECT *
WHERE {?s ?p ?o}
```

I would like that the data available in both folder are merged to form 
a new default graph for the query.

Thanks,
Regards,

Steven