Added disk usage logging! logs are written to api server.

Added disk usage logging! logs are written to api server.

Switched logic for readers, actual disk space is no longer examined,
instad it is the sum of the byte size of the collections (including
the manifest size) they requested to read. In rertrospect I should
probably report both the requested size and the size of the blocks
that actually appear on disk.

split reportUserDiskUsage() into computeUserStorageUsage() and
printUserStorageUsage(). Added logUserStorageUsage() to do the logging
mentioned above.

Moved command line argument parser out of the __main__ block so that
it can be accessed by other packages who wish to support commandline
arguments for this package even though they may have their own main
block.

Added new command line args for api server logging.

refs #2579 #1757