**8. Acknowledgement**

This work was supported by Slovak Research and Development Agency under the RPEU-0024-06 project, and by VEGA project No. 2/0211/09, as well as by EGEE III EU FP7 RI project: Enabling Grids for E-science III (2008-2010) FP7-222667 and also projects RECLER ITMS: 26240220029 and SMART II ITMS: 26240120029.
