Create a process to periodically clean the files on RPi and OpenMV boards

[matiasandina]

As it stands now, things get created but never destroyed. Ideally we would have a clean-up process where old files, once copied onto the central computer get deleted. Right now, doing it manually.

[matiasandina]

There are a few functions that trigger deletion of files. Some of the issues are:

• It's not automatic
• It does not check before messing things up

[matiasandina]

clean_cameras.py has been incorporated into the RPi shiny app. We still rely on user to know what is happening.