Stager API

Several scripts to monitor stager behavior:

* dirac-stager-monitor-file: Gives monitoring information regarding a staging file uniquely identified with (LFN,SE). 
* dirac-stager-monitor-jobs: Reports the summary of the staging progress of DIRAC jobs.
* dirac-stager-monitor-requests: Reports the details of current file staging requests, based on some selection filters. 
* dirac-stager-show-stats: Reports breakdown of file(s) number/size in different staging states across Storage Elements. Currently used Cache per SE is also reported. (active pins) 
* dirac-stager-stage-files: Submits staging requests for a particular Storage Element and file(s). 


Documented at:
https://twiki.cern.ch/twiki/bin/view/Main/StagerAPI