More local flushing, less VOSpace syncing

Changes:
-Output is now flushed locally after each source is accepted when processing candidates.  
-However, when working in a VOSpace directory results files are no longer automatically synced with VOSpace.  Currently this must be done manually afterwards.  
-Partial progress via processed indices are no longer tracked when working in VOSpace.  This means you will have to redo some work if you stop part-way through a file.  They are still tracked if the input directory is on your local file system.
-The username for the operator who processed a file in VOSpace is used as the value of the 'done property'.
-An output directory can now optionally be passed to validate.py so that output files can be sent to a different directory than the input files came from.