Action: remove unused import
Extract make_temp_scratch_dir function

Extracted this code from jsawrapdr_run and moved it to the
jsa_proc.admin.directories module in order to allow other
routines to make use of it.
Files: use check_output instead of Popen

This avoids an unnecessary use of Popen and also automatically
checks the return code.
Move restore_signals function to util module

This is to make it more accessible to other routines.
Extract open_log_file function

Extracted from jsawrapdr_run and moved to the jsa_proc.admin.directories
module to allow it to be used by other routines.
Admin: move timestamp creation to a function

This code was duplicated when make_temp_scratch_dir and open_log_file
were extracted individually from jsawrapdr_run.
CADC: add basic ingestion routine

Also added an "ingest" sub-command to the jsa_proc script.