rename getProcessingPlugins to listProcessingPlugins; completed initial documentation for experiment daq api; add target directory functionality for uploads

enhanced daq processing algorithm to avoid resource starvation between simultaneous DAQs and uploads

added new polling observer agent; enhanced upload functionality to avoid resource starvation with simultaneous daqs and uploads; resolved issue with starting uploads with large number of files in the specified directory

added stop-upload command; removed un-needed file stats; improved daq/upload reporting; cleaned up un-needed keys from catalog plugin

added user interfaces and utilities that enable experiment data download from machines that have ssh access to the storage host