We now check that a file is at least a few seconds old
before attempting to import it.
The actual minimum age can be configured in etc/config.yaml or
else is defaults to 10 seconds.
The idea is that this should give the OS enough time to fully
write the file before we import it.
The timestamp being looked at is the modification time.
Fixes#92.
If there is a problem with files matching the capture
globs but not matching the file name regexp patterns,
these routines will emit a message to stderr and skip
the non-matching file.
If their respective configuration keys are not
defined in a survey configuration, the import
routines will print an informational message
and exit successfully.
