#1286 SQL export issues

[Mey]

1. when I create a database using SQL command line named jabref it won't be recognized when I'm exporting and needs to be made inside the software.

2. When I export from different bibtext files to SQL it overwrites the data I had before instead of merging them together.

[Oliver Kopp]

We changed the way JabRef works with JabRef 3.6. Multiple users can now work on the SQL database. Please follow up at http://discourse.jabref.org/t/new-sql-structure/197