Several fixes

NEW: Interfaces Job API - added setSubmitPools(), setPlatform() sets ... "Platform"
FIX: TaskQueueDB - use SystemConfig as Platform for matching ( if Platform is not set explicitly
FIX: SSHComputingElement - use ssh host ( and not CE name ) in the pilot reference
BUGFIX: SSHGEComputingElement - forgotten return statement  in _getJobOutputFiles()