BibIndex: separate class for virtual index
- Introduces separate class for virtual index.
- Virtual indexes now communicate with their dependent indexes through queue table. This approach solves problem of parallel execution for virtual index. (closes #1661)
- Corresponding fixes for bibindex admin interface and regression tests.
Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>