Implement and add test for one-level directories.

ftp_upload.py:
- Add normalize_paths(), get_datelocdirs(), dir2date_loc().
- Modify dir2date() to not match dateloc dirs.
- Normalize any one-level dirs to two-level at start of
each main loop pass.

TestUpload.py:
- Improve comments in buildImages().
- Add build1LevelImages().
- Add testUploadOfTodayAndPrevious1Level().
- Add oneLevel flag to uploadAndValidate() and processing
for one-level directories.
- Change ls_sed command uploadAndValidate() to just
use "ls -sR" and no sed rather than "ls -lR" with sed
because there's some odd problem with ls -l outputting
inconsistent date strings.