Task #8887: getResourceUsages now gathers reource usages per resource per status. Made interactive charts for resource usage in web scheduler

Task #8887: removed obsolete getResourceClaimsForTask methods. Use getResourceClaims with task_id as argument

Task #8887: modified getResourceClaims so we can query for time-window, status, resource_type or task_id

Task #8887: modified updateResourceClaimsForTask to updateTaskAndResourceClaims which also adapts task/specification start/endtime, and which allows distinction between task_status and claim_status

Task #8887: added getResourceGroupMemberships method which returns the relation between resources and resource_groups

Task #8887: added broker as cmdline option. bugfix in _updateResourceClaimsForTask for converting datetimes.

Task #8758: merge from branch RA-Task8758 to trunk. svn merge did not work, so I used svn diff on branch and svn patch to trunk. For revision history, see branch.