Enhancements to output

[JackMostow]

Construct filename:

• FileList
• _
• tablet ID (serial number in case of Google Pixel C; gibberish for Samsung tablets)
• _
• YYYY.MM.DD.HH.MM.SS timestamp
• .txt

Do a more detailed ls of . (in practice, Download folder) that includes file date and size; anything else, e.g. version #?

Write to output file with constructed filename in top-level [main storage aka sdcard]/RoboTutor folder

[JackMostow]

Changed ls -R to ls -R -l to add file size and date.
Still need to include tablet serial number, if necessary from ..._TABLETID.json.